Copy the name of the existing certificate and then click Create a self-signed certificate

Change the date to next year

Here's the new one

Now you have two.

Next we need to find where the certificate was being used. We found two possible places:

Yahtzee!

Click in the box to see the new one. Select and save.

If you have one in Single-Sign-On, change that one as well...

Now delete the old, expiring one.