Instructor options are limited in this case. Instructors are not able to open the reviewing deadline for only one student for multiple reasons, one being that generating additional reviews after the reviewing deadline will also generate additional feedback tasks for other students.
One option is to extend the review deadline for everyone in the class. You can do this by clicking Edit Deadlines on the main Assignment Dashboard and updating the review deadlines and the feedback deadlines for the assignment. In this case, you will want to notify students of the change in deadlines and that they may receive additional feedback tasks to complete.
If needed, please contact Peerceptiv Support for additional guidance in this matter.