Select the required employee, and ensure you are at their personnel page.
Click over the finish date. The following is shown
For this example you are resuming the employee rather than changing the finish date.
Accordingly click
resume employee for the next dialog.
You can either enter a new start date for the employee, or leave the old one there.
If the employee has been gone for a while, it is best to select
New Start Date as the date entered then appears on your IR348 Employer Monthly Schedule as a new employee.