Border Run is suitable if you need to cross the border with Malaysia and get a new entry stamp to Thailand. Easy expedited border crossing is guaranteed accompanied by a qualified Thai employee. Choose a convenient day of the trip in the booking form at the bottom of the page.
All available services, see here.
If your current visa / stamp has expired at the time of the border run, you will need to pay an 'overstay' fine of 500 baht for each day of delay.
You can cancel your booking for free, not less than 7 days before the beginning of the event.
See other options for extending your stay in Thailand here.