What is the best way to obtain a new visa while in Koh Samui?

While in Koh Samui, you cannot simply do a border run to get a new visa; you must apply at the embassy. Border runs are not viable for actually obtaining a new visa, as they require you to go through the proper application process, which includes waiting 2-3 days for processing. One recommendation is to apply for the visa in Kota Bharu, where you can travel down on a Saturday, apply on Sunday, and return to Thailand by Monday afternoon, keeping in mind that the embassy is closed on Fridays and Saturdays.