As the manager of a pest control company, let me assure you that treating the yard is a waste of money and usually, almost always, does not work. I would recommend switching brands, say to Advantage brand, one with a different active ingredient in case your dog is becoming immune to the active ingredient in Frontline.
Otherwise, sounds like you're doing the right things, washing linens frequently, etc. The BIGGEST tip I give my customers, and this cannot be stressed enough, is the importance of vacuuming. Vacuuming will not only suck up eggs and larvae before they can hatch, but it sucks up dead skin and flea excrement that you don't even see, that is FLEA FOOD. And if you actively have fleas: vacuum obsessively! I'm serious. Hoover recommends that a proper vacuum is seven passes, a pass being both forward and backward = one pass. Most people do not make seven passes per spot on an non-flea infested carpet, so now factor in fleas, eggs and larvae. Not just carpet, but bare floors (remember cracks and crevices) and all upholstered furniture. VERY thorough vacuuming will make a HUGE difference.
Good luck.
I'm a contributing editor to Pest Control Magazine, and here is an excerpt from an answer of mine to a similar question that was published. Hope it helps.
1.VERY FIRST thing to do is get Frontline or Advantage from your vet (or online, as long as it is a reputable site and you are sure it's really brand name Frontline or Advantage). Some other professional brands from a vet are okay too, but I only recommend the two listed above, because they kill ALL stages of the flea cycle: fleas, eggs & larvae. Do NOT waste your money on Hartz from your local walmart. Fleas have been immune to it for many years now, it no longer works. You must treat your pets on the back of the neck with this first, to get them dying and/or jumping off your animals, where they will be deterred to return. Blood and dead skin is their food, so they cannot be on your pets. This way they can't thrive. Also, you should do this treatment every six months (or as directed on the package) for future flea prevention, especially if you have a pet that goes outdoors.
2. This may be the most under-estimated yet most effective thing you can do: Vacuum, vacuum, vacuum! I cannot stress this enough. Vacuum obsessively all over your house, carpets and floors and furniture, anything upholstered and even bare floors. Be sure to use the crevice tool for inside seams and around the edges of flooring. Whichever you have, canister or bag, change it at the end of each vacuuming or they WILL find their way back out of the vacuum. Hoover's official website says that 7 back and forth passes over each strip is an effective vacuum. That means: "forward and back = one pass", etc. Seven times before moving on to a new strip. So you need to really vacuum the heck out of all possible areas. This will do several things:
A). It will suck up fleas and eggs,
B). It will suck up dead skin from people and pets that are food for fleas,
C). It will cause the larvae in the cacoon stage to hatch early from the vibrations, making them easier to kill and shortening this whole process.
3. Next. Either A. Hire and exterminator at this point to treat the home (best option), or B. try do it yourself methods, as follows:
To treat yourself: Buy Borax, available in your local grocery and department stores in the laundry detergent section. It's usually called "Twenty Mule Team Borax", or any brand clearly labeled Borax will do. Buy several boxes. It's cheap and you'll need several. Borax dries up invisible eggs and larvae, preventing them from hatching. Go home and find a coffee can with lid, or Pringles can, etc, and poke holes in it to make a shaker can. Or use an empty grated cheese can. Fill it with Borax and sprinkle heavily on carpeting and pet bedding, and in cracks and crevices of hard flooring. CAUTION: Borax is strong! You should wear a dust mask while doing this, or be in a well ventilated area, it will make you choke if you breathe it in, so be careful. Don't touch your hands to your eyes or mouth until you are done sprinkling, then wash hands well.
Ok, so do this at least once a day, but the more the better. But leave it for about 3-6 hours at a time, then vacuum it all up, VERY thoroughly. Again, I cannot stress enough the importance of vacuuming a LOT. So after you vacuum up the borax, do it all over again. Sprinkle new borax, leave for 3-6 hours, vacuum up and repeat. Do this for at least several days to a week.
It is important that your pets be already treated with Frontline or Advantage at the beginning of this process or the fleas will just jump onto them for safety, where they will have a food supply and reproduce, and you will have a never ending cycle.
A side note: Be sure to vacuum the borax up very well in the pet bed areas, so they will not breathe it in when they lie down.
An exterminator can use chemicals that will make the process easier, so you need to decide if you have the money to opt for a professional, or would rather take the time to do this yourself.
If you follow the above directions and vacuum thoroughly at least twice a day, but really as often as possible, this should solve your problem. I have been sticking with the borax/vacuum method for years, and it has never failed.
Obviously, throughout this process, continue to inspect your pets and keep a close eye out at your ankles, etc, for any signs of fleas. You should notice them diminish, but it will take several cycles until they disappear. This can take a couple of weeks. Just because you don't see actual fleas, does not mean that they are gone. There's still eggs and larvae lingering that you can't see with the naked eye, so keep vacuuming, even after you see no fleas.
It's best to wash your bedding in hot water and immediately put it from the dryer to a plastic trash bag. Tie it in a knot and store it that way until the fleas are gone. The more things you can do this with, the less places they have to lay eggs. Obviously you will still need to have bedding in place on your bed, but consider washing and using the same set for the next week or two.
Remember, Vacuum, vacuum, vacuum. It can't be stressed enough. And never leave the vacuum sitting there without immediately emptying it into a bag which will be tied and brought outside to the garbage.
I guess it's better 
