I think you're missing the point
@L**
;
IF you apply for a yearly extension in August with a passport that's only valid until next January, you will get an extension until January. Period end of story. You ONLY get a year extension IF your passport is valid for a year from the date your current extension expires.
SO what you need to do is get a new passport BEFORE you go apply for a new extension. THEN take the old passport, the new passport and the letter from the consulate stating you got a new passport in thailand to the immigration office and get the stamps moved to the new passport.
There's no other way around it or all you're gonna get is an extension until January.