I am not sure when it happened but Salesforce CPQ now sets Start/End Date fields on Renewals. Instead of setting Start Date and Subscription Term. This is a bad thing for most of our clients. So I made the most simple process builder that sets Subscription Term to Renewed Contract Renewal Subscription Term and Sets End Date to NULL. This is a very specific use case and solution, so this may not be for you! If it IS for you, here are some install links!