Hi Kristian,
what about this one, did you tried it:
Renewing a Certificate using PowerShell
https://stackoverflow.com/questions/26248375/renewing-a-certificate-using-powershell
Looks like some users marked it as an answer, but pelease test in a test environment first.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Regards,
Stoyan