I think the rule of thumb is to replace it every 2 years or so. I doubt getting a new one if yours is only ~6 months old would make a difference.

I do think they will give you a new one for free though if you go into the store and say you are experiencing connection problems (worked for me anyways ) I have gotten a slightly better signal and have been dropping less calls, but the problem with it failing to reconnect in low signal areas still remains.