@เฮนนิ่ง ***********
you need to be talking to the uni you attend. Most of the immigration offices will let you get a new extension when you have 30 days or less left on your current stamp SO if you can get the documentation from your uni and go to the immigration office to apply for a new extension BEFORE you leave there's a good chance they'll issue it. AND
Seeing as real uni students get extensions either by the term (every 6 months) OR by the year if you get an extension and a re-entry permit you'll be good to exit and then come back in on the valid extension