This would be, what, 3 litters in a little more than 3 months? I can see why you are worried. If it helps any, carrying a litter is nowhere near as hard on a doe as nursing is, so the first litter that she lost almost doesn't count. If you haven't done it already, mark the date on your calendar; you could lose track of the doe's possible due date with so much else going on. With a little luck, she didn't breed, but it never hurts to be prepared, just in case.
If you haven't been doing this already, I would add some Calf Manna pellets to the feed that the doe gets; either that, or mix some dry milk replacer powder with dry rolled oats and offer that in a separate dish. I'd add the rolled oats in any case, since your babies are getting old enough to start eating solid food.
Watch the doe's behavior; if she starts acting like she is digging a nest and/or carrying nesting material, you know what comes next. I don't like to wean kits that young, but if the doe acts like there is another litter on the way, it would be better to get her current litter out of her way a few days before the new kits arrive - and that means putting them in another cage.