It depends on why you are doing the restoration.
If appearance matters, I would remove and recoat. Apparently, there are still shellac based conformal coatings still available for authenticity. Otherwise I would switch to a lacquer or another varnish based coating. Removing it could be a tedious job or very simple. Depending on what else is on the board, a few minutes in an ultrasonic bath with denatured ethanol or pure ethanol will work. If there are transformers and relays, etc. on the board, I wouldn't do that. Then it would require gentile cleaning with a brush/swab. The nice thing about shellac is that it is simply solvent based in contrast to enamels that are reactive. Thus, applying a good shellac solvent/thinner, letting it level, and slowly evaporate may repair the finish cosmetically. All of that assumes it's shellac.
If appearance doesn't matter, then I would leave as it is.