Hi!
I'm 15, and bipolar.

I think what you've mentioned is a good idea. Make her earn her dance lessons. Talk it over with the coach (so she doesn't get kicked off for missing lessons) and every time she does something wrong, she either has to stay home, or her coach will discipline her in the lesson. (Running laps instead of dancing, ect) its really important that you keep in close contact with her coach, principal, teachers, and therapist. The most important thing is for her to know she can't get away with things. Make it clear ( perhaps put it in writing, and have her sign it, like a contract) what behaviors will earn what punishments. For example- Disrespect to you or a teacher equals an apology letter and 25 minutes of jogging at her lesson rather than dancing. A second offense that week means she has to jog an entire lesson with the apology letter, a third weekly offense, and she sits out the next recital/competition.

Hope this helps, and feel free to PM me if you want some perspective from a girl her age.