They have a pretty good system in Vientiane these days. Actually using a queue system that makes everything more efficient. I wish other offices had easier systems.
I really only know about volunteers and it's convoluted with social department into the mix also, but if you have a work permit, a letter from social, you get a one year visa. I can't see why flying to get a new visa is simpler/cheaper than immigration. The lawyer has to prepare documents either way and new visas have got to impact work permit applications.