Have you considered a paddock system. A paddock system is where you take your pasture and divide it into smaller units of pasture. It could be done with permament fencing but the easiest method would be electric netting that is easily moved. Essentially you place your chickens in paddock #1 for an allotted time, which is the time it takes them to eat the grass down but not kill it completely. Then you move them to Paddock #2, you keep rotating them through the paddocks and by the time you get back to #1 the grass has recovered and is at full height again.
# of paddocks is dependant on the size of your pasture and the # of chickens you have and how long it takes them to eat down your grass. I'm actually trying it this year with my sheep and alpacas because last year I couldn't get grass to grow in the pasture because they always kept it short. This year I've created a few paddocks and I'm seeding the empty paddocks and waiting for the grass to return to full height before I actually start the paddock system, but it seems to be a very doable system for most people.
That sounds like a very good idea if you have the space for it! Rotate the pastures so you've always got grass growing somewhere.