Depends. If you are good at Chinese, you might just be wasting time. I spent two years in Taiwan as a missionary and learned Chinese, and afterwards wanted to get a minor in it. My school's program is a joke, and I haven't really learned very much in the 400 level classes. If you just want to have fun, then maybe take a class or two, but if you are serious about learning Chinese then just study the Characters on your own time. If you're already fluent I can't imagine why you wouldn't at least go to Chinese 202, even at a University with a more prestigious Chinese department.
I am a white boy; taking upper division Chinese classes adds credibility to my claim of language proficiency. You are Chinese, so you don't need anything on paper to back your claim that you are fluent. If anything, you taking a 100-level course makes you look like you are not as fluent as you claim to be.
