There are plating shops in LIC and the Bronx. If you don't want to spend much money, then fuggehdaboudit. And of course you have to remove the fork, silly! To rechrome, you first have to remove all the contiguous old plating (most usually 3-layer, copper, nickel, chromium) then refinish mechanically (chrome finish is only as good as the substrate), and replate. It takes time, and it's hazardous and environmentally harmful, meaning (among other things) that disposal is expensive.