Closed assessment cycles can be reactivated. All open tasks will reappear, and the assessments will be editable. Any participants with open tasks will see them again in the review module under 'Open tasks,' as well as receive a weekly reminder to complete the task. There won't be a new kick-off email.
To re-open a closed assessment cycle, navigate to the Reviews module tab, and click 'Cycles' on the left-hand sidebar. Filter for cycles that are 'Complete' to see all closed assessment cycles. Select the desired one by clicking on the name. By clicking 'Re-open' on the top right, you unlock the cycle.
Read more here to learn how to unlock an already submitted assessment within a review cycle.