The update_account command was added in certbot 0.30.
Looking at the release notes from then, there might be a register --update-registration command that could do what you want in the meantime, but I'm not personally familiar with it.
And that's getting old and probably not getting updates. You should upgrade to a newer in-support OS (which probably includes a newer version of certbot). If you're not up for that just yet, you might also look into updating only certbot by uninstalling the version in the package manager, and then installing a newer version via snap or via pip. But just be aware that even if you're getting a certificate, there's a lot more to actually being "secure" and part of that is ensuring that your system is getting security patches.
The email on the account is actually much more important for getting notifications if Let's Encrypt has some other issue with your certificate. The expiration emails are just a last-ditch effort to remind you to check on your other automation; you shouldn't have a process relying on them.