I don’t know of a way to strip the plating without stripping the
base metal as well. The rhodium, base metal, and solders will strip
at different rates. Stripping seems like more work in the long run.
The problem you may be anticipating is that the old rhodium plating
is harder than the underlying metal, thus polishing over the repair
zone leaves a small step or a frosty zone where the old plating
ends, that is visible after replating.
The best way to overcome this is to sand the repaired item so as to
leave the edges of the old plating at the corners (either external
or internal), and avoid having the old plating fading out or
feathering off on plain surfaces. For example, sizing a plain wedder
will require sanding all surfaces. Sizing a diamond solitaire
requires sanding the whole shank but not the head. being careful to
sand right up to corners or joints. A light sanding with 600 grit or
finer is sufficient to cut through the old plating. Polish and
replate! If the old plating is discoloured, the new plating will