Yeah, well, so it goes. Wait 'till next year! Eventually, she's going to get to do it, one way or another.
WRT to your daughter... They don't have as many kids go out for HS Musical as they'd like, so pretty much everyone who auditions gets in. But a lot of kids end up in the Ensemble, and often it's kids just like your daughter, who can sing but not dance, or dance but not sing. The simple solution would be for her to take a few dance lessons before next year (unless she's a senior, of course) -- and NOT give up.