First use acme.sh to renew the certificate. Then as one example,

cat /root/.acme.sh/tsterm.com_ecc/fullchain.cer /root/.acme.sh/tsterm.com_ecc/tsterm.com.key >bundle2406.pem
curl -X PUT --data-binary @bundle2406.pem --unix-socket /run/control.unit.sock http://localhost/certificates/bundle2406
curl -X PUT --data '{"certificate": "bundle2406"}' --unix-socket /run/control.unit.sock http://localhost/config/listeners/*:443/tls
rm bundle2406.pem

No need to restart the unit service. The new certificate is configured now. Lastly to clean up the old certificate,

curl -X DELETE --unix-socket /run/control.unit.sock http://localhost/certificates/bundle2404

To check the uploaded certificates,

curl -X GET --unix-socket /run/control.unit.sock http://localhost/certificates/