So, what I would recommend is always ask her to join you to dance, and if she says no, playfully enforce that she does, because chances are if she went to the prom WITH YOU she wants to dance WITH YOU. If she says she can't dance, quickly teach her.
You'll also find that the biggest reasons for her being boring is that she's shy or nervous. Break the ice, have a friendly competition, not a race or anything, but do something that suits her personality. You'll soon notice that even if you're not interested in a relationship with her, you will actually become friends if you try to make sure that she's involved in everything you do and basically just makes sure that she has fun.
The secret to you having a fun night, is to make sure that she has a fun night. Because then that will be her mission too. Good luck and remember to just have fun.