I will start saying that I can be wrong about that.
BUT
Do your best friend knows about it? He can help, give some tips. Make it happen faster.
You both can have a party at his/her place. Small thing. Here in Brazil we call "esquenta" when we get drunk at someones place before going to the actual party, that can work too.
When this "esquenta" or party happens pay attention to when she gets alone, I don't know, to get a beer or food, someplace that you know that will be that time constrain, and you talk to her normally, smiling, like that warm feeling between you both never died. Hopefully she will start drinking right in front of you and you say something like "remember when we bla bla bla?" (in a FUN way). That memory should put her mind at that time when she liked you. Perhaps finish it with a "I miss you" *hug* (strong kino. 80+ on The Sims, yo) and give her a long stare in the eyes with a smile so she knows there something more". Then 1) Perceive a KC moment or 2) Ask to come back to your friends 3) "We should talk more often" (or "see each other...?" - can't judge if this is to forward).
But I can be DEAD WRONG about it.
I'm curious though, let me know the result bro^^