Babybaby,

Two things you can do.
Ask her if she still feel the same as before, just remains friends. Ask her if she has changed her mind about that. Ask her if the two of you can go on with your lives separately. That is a gamble but it will clear up the air between you and her.
Or, do what I did when I was dating a classmate in college. I didn't know how to ask her to go steady, although we were very closed. So, one night when I was about to go home I asked her: Can I kiss you goodnight? She said yes(Patok).