There are re-entry permit desks at Don Mueang and Suvarnabhumi. They are open
****
.
You can have all the copies, photo, form and pay "face value" (1000 baht single, 3800 baht multiple)
or
you can just show up with only your passport and pay the 200 baht service charge (along with the reg price) and they'll sell you one too 😛 (1200 baht single, 4000 baht multiple)