the quick answer: if you're not attracted to her whatsoever, don't date her.

the long answer: if you still feel a little flicker in your heart from way back when- take a chance on her. if you can still look at her and think she's pretty, then go for it. do you enjoy talking to her and spending time with her? does she make you happy? can you close your eyes and imagine yourself going to eat dinner with her, or to the movies, or laying in bed with her? the fact that you had a crush on her in the past means that you once found her attractive, the question is, why did that attraction wear off? did something about her change, or do you think you could find in her once more, that which you were drawn to in the first place?

some people say that sometimes love can be a slow burn- that it's not as exciting as the lovey dovey rushing sensations, but that it's stronger and longer lasting. it seems like you already have a really nice friendship with this girl. if i was in your shoes, i would weigh up the above, but also "do i want to risk ruining the friendship i have with her already, at the price of trying a romantic relationship with her that might not work out because of my misgivings towards the idea?"

maybe you should have a good chit chat with her, and see how she feels? ask her why she has feelings for you, ask her what she likes about you- ask her why now. her answers might shine some light on the situation for you :)