The OCP script handles the KFMon install package just fine for that very reason

.
NickelMenu/KOReader/Plato persist through updates just fine.
KFMon doesn't, for safety reasons (an unexpected behavior change in Nickel could otherwise result in a boot loop).
You can either:
* Run the OCP install script on one of the full packages again, as reinstalling KOReader/Plato is effectively harmless.
* Run the OCP install script on the KFMon install zip archive only.
* Switch to a pure-NM setup (the config files are installed in the .nm folder, with the relevant entries commented out).