Hello @Ryan Kohn !
Hope you are having a great day!
Thank you for asking a Question! We are Glad to Assist you!.
If the federation certificate has already expired, you need to remove all federated domains from the federation trust, and then remove and recreate the federation trust.
I am afraid, in your situation you will have to remove it and get it repalced.
Please go through the link mentioned below inorder to remove a federation trust.
After you have removed the Federation Trust, Visit the link mentioned below which explains how to renew the Federation Certificate :-
Let me know if the above solution resolved your issue!
|- Please don't forget to "Upvote" and "Accept as answer" if the reply is helpful -|