i think you answered your own question if you stop to think about it... Since the TB runs over the sprocket you're going to need to remove the belt to replace the sprocket - if that is what you were asking. If the TB is still in good shape there's no need to replace it or the tensioner, water pump, cam seals, or anything else that is in the "entire timing belt" service protocol - just depends how close you are to your scheduled TB service. Always a good idea to replace the cheap stuff that can cause problems down the road though, so personally I'd splurge and get some new radiator hoses, belts, and cam seals - unless they were virtually new.
