sbhkma is right, training is key. If you just stick her on the runner and leave her there, she is able to sit and obsess over those chickens the whole time she's outside. So, what happens when she finally gets off? Well, you already know that. Training her will take a lot of commitment on your part, but it will be worth it and it can be fun for you and your dog. Not too mention the opportunity you'll have to bond with her and the chance for exercise that will (hopefully) tire her out. I had a Lab mixed with something, he was a really terrible puppy. Always into to everything, chewing on everything, trying to wander and chasing critters. He ended up being the best dog after he got past his puppy phase. Labs are bird dogs, they like birdies very much. The idea is to set your dog up for success and do everything in your power to prevent failure.
I'm pretty much in the same boat as you, except I have a 5 month old Doberman Pinscher. We've, and I say we because my whole family trains her, been working on leash training for a while now. And that leash comes in very handy while training her to ignore the chickens. We spend a good deal of time just sitting next to the run, practicing her watching me, leaving various object alone and other general obedience type stuff. It took us a while to make it next to the fence though. We started in the yard, well away from the coop. At a distance at which she would ignore them and moved closer as she progressed. Now she is able to be off leash with the birds in the yard (I have Silkies, they have no chance at getting away from her), but she is never left outside alone with them because she will occasionally get a wild hair up her butt and be naughty. At which point I call her back to me and put her on the leash to do some training- which she enjoys very much. This is a tried and true method for me, its worked with my black Lab mix, my Bulldog and seems to be going well with my Dobie.
There are lots of great training videos on Youtube. I really like the ones by kikopup. Or you could always go and register her for obedience class, its never to late to start a class with your dog.
Good luck