I would guess she's not pushing up enough through her shoulders or bringing her knee close enough to her chest. It's hard to work on this one at home and I honestly haven't come up with a whole lot of super helpful drills for it at the gym, except to have them practice it a lot. If she needs work on some other bar skills as well, this is one situation where I think a private, even a 1/2 hour one, might help if you can get one scheduled. Of course not all gyms offer them...I'd just talk to the coach about the possibility and see what they think about it. I probably wouldn't do it just for the one skill, but if there are several areas that need to be addressed, it might help to have some undivided attention.