Tone's idea is an interesting one, but why recipricate back in 'the game'? I think you should ask her straight up. You should tell her what you told us. This shouldn't be much of a problem since you said you two were good friends before, and you two seem to talk often.
Just ask her if she likes you, if she wants to take it up to the next level, etc. If she gives a bashful smile, then tell her you want more than that. If she says she wants to concentrate on school, ask her if she means that she wants to stay platonic. I'm sorry, but you can't just stop yourself from having feelings for someone (so, the whole 'I'll become too emotionally invested and wouldn't be able to concentrate on school" statement is bullshit to me. If you like someone, you like someone... there's emotional investment if you like someone, period). So, I believe you should talk to her upfront, and not settle for answers that have 'mixed signals' written all over them.
If a dream comes true... then is it still a dream?