I hope mine is not the best answer, but if you can't manage to prevent the expiry you at least need to be prepared for an attempt to 're-register' your domain.

I hope mine is not the best answer, but if you can't manage to prevent the expiry you at least need to be prepared for an attempt to 're-register' your domain. When your domain does expire it will end up on a 'just expired' list and there are a bunch of bots auto-registering every expired domain that looks remotely interesting. If it gets that far, at least make sure you're prepared to try and snatch it before the other bots get it.