Renew it, but do not expect big changes. In airport mode my n900 stays alive a lot of time. However, always connected by 2G (and wifi disabled) my n900 dies fast.
I suspect that to be connected to skype and gtalk all the time is somewhat related. But an iphone 3gs with 3G (not 2G, 3G!) and the ebuddy (=gtalk) running all the time, lasts almost twice (>1.5) than the n900. Conclusion, I am losing my loyalty to maemo devices.