To renew all LetsEncrypt certs that you have, there is a nice Bash script. Download this script in /etc/letsencrypt, and make it executable.
cd /etc/letsencrypt/ wget https://dl.eff.org/certbot-auto chmod +x certbot-auto
Now in your crontab or in your shell command, you will have something like this:
0 6 15 * * cd /etc/letsencrypt/ && ./certbot-auto renew && systemctl reload httpd
Adjust it for your needs.