Each new firmware file generated will have a unique serial number. If you would like to upgrade the EEPROM on an existing cape, you will need to issue the EEPROM to the same serial number. This will require you to enter the email address you used for the initial generation.
In order to access the components of the EEPROM that requires a signature, you will also need to install a valid licence onto your FPP instance. Instructions are here.
For more information on this generator, please see the Morton Lights Blog.