How do I renew my Non-B visa in Vientiane and what should I consider for the trip?

I agree with

@Liam ****

, get an early morning flight to Udon Thani and then go to the Nong Khai border, cross into Lao and get to the consulate to tunr in your paperwork. The next afternoon pick up your passport, get to the Nong Khai border, enter thailand and get to the Udon airport in time to catch an early evening flight back to bangkok.

That's the fastest and easiest way to do the trip.

If you need to go to Vientiane (notwithstanding the comment above), it's much cheaper to fly to Udon Thani, and hop across the border from there. You also need to remember that you apply at the Thai Consulate in Vientiane, not the Embassy. I would advise you stay somewhere near the river and get a tuk-tuk (or even rent a bicycle) to go to the Consulate, as that area is a bit of a dead zone at night and you won't find anything to eat/drink/do. It takes 2 days, i.e. you apply in the morning of day 1, get your passport back afternoon of day 2. If you fly via Udon, you can take a 6am flight up there, and make it in time to apply, and get a pm flight back meaning only 1 night is necessary. Try to avoid applying on Mondays as it tends to be very busy and the wait times are quite long

You can not re-new you non B visa, you can visit a Thai Consulate or Embassy and apply for a NEW Non Immigrant B visa with all the documents needed. Or 30 days before the last day of Admitted to Stay you can visit your local Immigration Office and apply for a 1 year Extension of Stay supported with company documents.