Navigate to the event you want to reschedule by:
Clicking on the associated event from Google Calendar.
Clicking on the name of the event in the add-on side panel.
Find the scheduled event.
Click the calendar icon labeled Reschedule.
A pop-up will appear with options of how long to push the Task Event to the future.
The reschedule icon
Pop-up with options for rescheduling
Refer to Remove scheduling exceptions from the Google Calendar add-on to clear any scheduling exceptions.