Thi KB explains how to renew the SSL certificate for the SEGv2
It depends how is configured on the console
If you did not use the option "opload locally", then you can simply upload your new cert in the SEG v2 config screen in the UEM console.
Once done, restart the SEG server and it should pull this new certificate automatically.
As of SEG v2, SEG will pull all configs via the MEM configuration ID through API calls.