Is she bleeding at all or is it just split? If she's not bleeding, she should be OK - just watch her. I had a chick hatch this spring with 1/2 her top beak missing.
Commercial hatchery's debeak them. A chicken can get by fine without the top beak. You will want to keep an eye on her to make sure isn't being picked on too badly .
If you feed your chickens free choice and they always have acess to food, it should not be problem. It may take her a little longer. The only issue could be if she is having to compete for food she may not get enough. If this is the case, seperate her for about 30 minutes a day and feed her while she is alone.
I had a roo this year who had a beak where the top went to the left and the bottom went to the right. He wasn't as big as the others but he was fine.