about the visa application and resident permit date

hi .. i am currently studing in sichuan university, chengdu ,sichuan.. my old passport has residence permit till september 30,2012.. but this june i am going back to nepal for my summer vacation and i want to make a new passport as the validity period is going to finish. so do i again have to apply for new visa in nepal to come back to china or will the resident permit in my old passport will do the trick.. thank you