If I wash down my bike after a muddy race cross race or training ride I usually dry everything off and then begin lubricating the chain and sprockets back up once it has dried. The only place I don't do this is the bottom bracket, it this something I should be doing as I have gone through one bottom bracket per year for the last three years or is this normal?
Modern Cyclo-cross bikes typically used bottom brackets with sealed cartridge bearings. No real maintenance required, except to replace when worn out. When cleaning your bike, be careful as high water pressure can force debris past the seals and into cartridge bearings. Once a year replacement is pretty typical for bottom brackets with outboard bearings. Sad, but true.
As an aside, why are you lubricating he sprockets? This will attract dirt. The only place you want lubricant is inside each bushing on the chain and really no where else. This is why everyone talks of wiping a chain down after lubing (and allowing time for the lube to penetrate the bushing assembly). The only reason I can see for leaving lube anywhere else on the drive train (e.g., sprockets) is if you have inexpensive components that rust easily. Even then, a little bit of surface rust doesn't really affect drive train performance, it just doesn't look pretty. (Surface rust being the key, a chain rusted into a giant block is of course pretty inefficient to pedal on.)