okay son, the reverse lights are controlled by the NSS, ( neutral safety switch) located on the side of the transmision, I assume your talking about an automatic trans. Its a very common problem on these jeeps. It is an expensive switch to buy, approx. $3-400. Most people remove it from the trans, take it apart and clean it out, this usually works. Here is a write up on the whole procedure, click on this link.
http://jeepin.com/features/nss/index.asp