I think some guys here said most boards last ~150 days of riding or so, less if you hit rails. I can't really think of a reason why your board would be in need of replacement unless...well, some of the bananas apparenty lose pop over time. Other than that, can't really think of anything.
Well, that or if you want a board thats completely different...this year (first board) was pretty stiff, so I wanted something more park-ish, like a Mini or stairmaster but found a Gnu RC dirt cheap.
Bindings: Burton Missions 07
Boots: Burton Freestyle 07