Originally Posted by Live and Learn:
To be honest I would not have give her 2 chances/warnings not to hit. You know her well enough to know she will hit every day. I would say from now on ZERO chances/warnings.
I would give her parents notice to get on top of this or you will term.
Imagine how your other dc families feel about their children being hit and kicked.
I have a zero tolerance policy for violence here. My #1 job is to keep everyone safe in my care. 
I think it sounds like you found the 'Hot Button' if she wants to get away with hitting without getting sent out.
I agree with the Zero tolerance at this point too. I would make sure to tell her that I am keeping everyone safe so you have to play alone, and I would do it to keep you safe too if someone was hitting you.