I got my belly pierced twice and it rejected both times. The second time it rejected sooner. I'm about to take the belly ring out and wait until the summer to get it re-pierced so it can heal. Is it true that it could reject again? My friend told me that if I get it pierced with more skin then it would help and that the scar tissue I have would make it harder for it to reject, is that true?

If it has already rejected twice, it is a very very high chance it will reject again. Rejection is basically your body's way of getting rid of something that it doesn't want. Your body sees it as a foreign object and it needs to get rid of it. No matter how many times you pierce your navel, it will more than likely reject every time. Some people have luck with navel piercings, and some don't. You must one one of the ones that has bad luck.

Even if you pierce it with more skin, less skin, in a different spot, etc. your body will still see it as a foreign object and try to get rid of it. I'm sorry you've lost money and piercings on rejection. Its unfortunate, but at least you know your body is doing what it is supposed to do. :)