To reschedule a lesson, start by cancelling the already-scheduled lesson. The counter for your unscheduled lessons will go up by the amount of lessons you cancel.
Next, follow the process for scheduling a new lesson. Go to the Lessons screen and click on the Unscheduled lessons counter. Click on Schedule for the purchased lesson packages for which you have unscheduled lessons.
On mobile, click the menu icon on the top left of the screen. Select Lessons and cancel the lesson you wish to reschedule.
Next, select the Schedule option for your now unscheduled lesson, and select the date and time that works for you.