Regardless of the state of the current first Visit on the Job Board, single left click and choose Edit.
Click on the Job banner box
By default, you should now be on the Visits Tab
Now click the big Plus button in the right hand corner, this will add a new Visit.
Now tap the Scheduled Date and choose the date for the next time you need to return to this customer for a return visit.
Fill in all of the rest of the information accordingly.
Press the Save button in the bottom right-hand corner.
Finally press the X in the upper right-hand corner.
You are now returned to the main Visits screen and you will see both Visits. Also if you go to the date on the job board for the return Visit, you will see it added on that day.