I'd think something like that might be fairly expensive. There's the work to do the soldering/braising and then the work to re-knurl the handle, is what I can think of.
What I'm saying, is a new handle might be cheaper.
Mostly every silver plating service provider will get it done, but beware of the one who are cheating you as many of them mix other chemical and cheat you. I know a place where it is done and they I trust them very much as they are genuine and always deliver the quality work. Recently I got my jewelry and some of the living room cupboard plated. They provide a very smooth finish which makes those things more loveable.