Sorry, once chipped, scratched, or otherwise damaged, there's nothing you can do.

There's no way to "fix" a chip, and all you can do to is to keep a light coat of lube or wax on it to prevent moisture from infiltrating under the nickel and rusting the steel.
As long as you don't hit the area it shouldn't flake off or spread.

For wax use Johnson's Paste Wax or Renaissance Hard Carnuba.... NO CAR WAX.