If a Recurring Shift should end at a fixed date then this can be entered by defining an expiration date.
While Adding a New Shift or Modifying an Existing Shift, scroll down to the Recurring Schedule section and select Define Expiration.
The screen expands to show the Expiration entry section.
Enter the expiration date by clicking in the date box and selecting the date from the date picker.
Select 
to save the shift.
The recurring shift will now end on the last recurrence before the expiration date.