How can I make sure that I can revert products back to the original price

Products will revert back to their original prices if you set an end date for the schedule.

That way, prices will revert at the end date. Or, they will revert when you press the deactivate button.

Already run a schedule and need to undo it? Open the schedule, find the run in its timeline, click View details and use Force Revert — this restores each product to exactly the recorded before state.