With the default setup, auto-renewal attempts start 30 days before expiry (so in ~50 days for you), will retry daily, and 10 days before expiry you get an email warning (assuming an email was provided during setup), which allows you to then check the Let's Encrypt logs to see what's wrong; once fixed you can "sudo certbot renew" to try again.
But yeah, if only your ISP has changed, that presumably just means your firewall has been configured with a new gateway IP, and there's no reason for that to affect Certbot/LE.
Well... unless your new ISP is incredibly idiotic and block the Let's Encrypt verification - but it's all on standard ports/protocols so they're not going to do that.