I really don't know any other way to get rid of neediness and replace it with solid persistence, other than just going out and getting other girls. A lot of times, I think we start to accumulate what we want from a girl, and stick it all into one chick. This is where oneitis comes from. We think we "need" a particular girl because in our minds, we have equated this girl with what we ant. It's actually a form of settling.
This does not mean that this girl you want is not completely worth it. But rather that you just have unrealistic expectations of her, and it's going to throw everybody off. Go out with other women, make out, have sex, whatever, and you should burn off a lot of this "neediness". In the end, you'll actually end up appreciating this girl more, but for
who she is, rather than
what you want. Weird, huh?
Hope this helps.