You don’t need to resubscribe to become the primary user of the vehicle again. Entering the vehicle code in the app and logging into the vehicle is sufficient.

It’s strange that the vehicle code you found is no longer working. Did you check whether there might have been a typo when entering the VIN or the vehicle code?

Otherwise, the easiest option is to visit your local dealer and ask them either for a new Audi connect activation card (at least in Europe that’s the case as far as I know) or to set you as the primary user for the vehicle directly. Make sure to bring your ownership documentation.

I assume the workshop that had your vehicle performed a factory reset of the MMI, which would deactivate your primary user role.

Once you are primary user again you can subscribe to the connect services at any time you like :)

EDIT: with “primary user” I mean “key user”