Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
That's ACME client specific. Unfortunately, it seems there is no question "What is your client" in our questionnaire. Would you be so kind to share the name of the client you've been using?
Simple just dial 1-800-RENEW-ME
[Just kidding - there is no simple answer to your question and no number to dial for instant help with it.]
To (comically) expand on what @osisris has explained.
If you asked me "How do I get to Carnegie Hall New York City?"
[we all should know it takes "practice, practice, practice" to get to Carnegie Hall]
I would first have to know (many things before giving you a reasonably accurate response):
Where you are coming from?
How you would like to "travel"?
How soon do you need to be there?
In that sense, this is a very similar situation.
The more information you can provide the better the answer can be.
...and to perhaps give a little bit of possibly helpful information, if whatever method you used to get the cert in the first place doesn't handle renewals automatically (as it should), do it again.