Yes, you can edit the End Date of any Active Anniversary Campaign to any future date than the current date or you will receive the error below:
Note: Anniversary Campaigns can be created without an End Date which will make the campaign run indefinitely. If you add an End Date and would like to make it run indefinitely, you cannot remove the date but instead can set the End Date to a very far date into the future.
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)