Remaining the prize...
1) Don't call for a few days, see if she dials you. This can be risky because if you let her slip to far and another guy moves in, your fucked. But it is a good test to see where your at in her heart.
2) Next time you call, act like you have another call and tell her you'll call her back in a few minutes. Don't call back until later, or wait for her call.
3) Step up the cockiness, wittiness, and funny attitude. This always works.
4) As someone above me said, when you go to kiss her, turn away and resume watching TV or whatever the hell your doing.
5) Jealously. Make her fucking jealous. This works like a charm, all the time. Next time your with her, point out a beautiful woman (not in a dorky way) "Wow, shes gorgeous" works, just keep it more classy than "Wow shes hot!"
There are tons of things you can do. As said above me, become unattainable. EVERYBODY, not just girls, wants what they can't have, its simply human nature.