Can a workflow update a contract record when the contract record is already in an Active Status (read only)

Hello,

I have a workflow that is based on the contract record.  On the record there is a renewal notification field and if the renewal notification value is 60 days then it is supposed to update the Contract record and set the Renewal Notification date to 2 months prior to contract end date.  However, this fails because the contract is already in a active status so it is read only.

How can  make this work?

Thank you.