Actually, I just got the certs renewed with slightly same manner.
$ mv /etc/letsencrypt/accounts/ /etc/letsencrypt/accounts.off/
$ # and then
$ certbot-auto register
$ certbot-auto certonly --webroot -w ... -d ...
again to get fresh certs. Don’t know if this is against the Let’s Encrypt policies but at least I got a green lock from now on and no longer pinging ACME too much.
Thanks @ahaw021 for your contribution!