there are sharpeners on the market- i have one in a drawer- i've had it for 8 years- i've used it a couple times- i hate it- it is dangerous- and only helps for a limited amount of time- i would rather spend the $$ on new blades than deal with that 'handy-dandy' gadget.
but i keep it around- in case a day comes when i have no $$ or no way to get to a new blade and need one==right then (and pray that day never comes)