@Pradeep Kumar Ramagiri Thank you for reaching out to us, As I understand you are looking for approach for renewal of expired certificate for app registration.
Similar requirement has been discussed in the below links, you can follow the steps mentioned here to update/renew the certificate in the app registration
https://rakhesh.com/azure/graph-cmdlets-and-azure-ad-app-registrations/
Let me know if you have any further questions, feel free to post back.