If you're going to go anyway, then you initiate the terms. The time, place, where to eat, etc. Keep things light and lively. When you interact with her, show her interest as if you were dating her for the first time. Someone once told me that when my W talked I should listen as if she were the only one in the room, which (of course) is what I did when we first dated. It worked.
Don't expect anything out from the evening. Let it flow but still maintain a certain level of detachment.
It's a hard balancing act, but you can do it.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.