If you like your bike, I'd say there's no *good* reason to get a new one. If you're itching to try something newer, see if you can borrow a bike from someone for a weekend or something. Or hook up with a local cycling club, make lots of friends, and try out their bikes.

Also, it's good to have an idea of what kind of riding you want to do before you start testing things out. Do you want to go super fast? Commuting? Touring? Leisurely rides? Long distance?