I don't very often... I know you can replace the blades, but I don't even do that. Usually use them until they don't work anymore.
Before I deployed I bought a new one, it is curved to contour to your head... not convinced they are any better than the "normal" ones.
When I got here and saw all the cool kids growing 'staches, knowing my cheesy child molester 'stach wouldn't be impressive enough, I opted for growing a combover! I've shaved my head for the last 18 years. 9.5 months later, I've got a pretty sweet combover. Not Donald Trump sweet, but close! Pretty awesome when it gets windy! Headed home on R&R today... told the wife I'd come home with it and shave it off the next day. So now I can check "comb over" off my bucket list and go back to low maintenance! lol