First of all, follow the steps outlined in the article below if you have not as yet set up Approver and Reviewer Reminder Emails: 

• How to Set a Number of Reminders for Policy Reviewers/Approvers

Once this has been actioned, Reminders will then be sent, on a weekly basis, to your Approvers and Reviewers up until the 'Approval Due Date' that has been set within the Policy. 

• If the 'Policy Due Date' has lapsed before the first scheduled weekly reminder is due, then a reminder will not be sent. 
• Reminders will only be sent if the Policy Due Date has not passed.