My situation is this. There's a girl who 'used to' like me and I fell for her. I screwed things up quite a bit a few months ago (needy). Learnt the lesson the hard way: rules to protect yourself from being hurt, are there to protect yourself from being hurt!

If I somehow 'reset' things, show her that I'm a different guy now (which I am), will there always be that possibility of attraction? (when she has liked you as a crush in the past, not as a result of gaming her).

Basically, the question is this, once a crush, always a crush (girl's crush on guy)?

Let me know what your opinion is, based on your past experience and with girls in general.

Not exactly. Attraction has a expiration date.

I would say, not ALWAYS, but the chances of yes can reach 99% if you keep your game up. Game is game, there is no "expiration date" if you keep yourself at value, that's what you'll be. Valued.
That means, don't be needy! Haha. Glad you learned your lesson, I have too.