Reverse or Invert Flight Plan

Tap the edit button under the flight plan (first of the 5 buttons) to expose two rows of buttons under the flight plan. There are two buttons, one to invert the plan, and one to reverse the plan.

For example, you have a plan A-B-C
Reverse will change the plan to A-B-C-B-A (back to origin)
Invert will change the plan to C-B-A