Don't take my word on this because I am no expert, but this came from Gary Bard who I hear speak last night, he is one of the original AiARE instructors (and i believe founders too).
1) He said since they overhauled the level 1 curriculum a few years ago, you can take sequential courses in any state. They have toned down the emphasis on types of snow in certain regions/snow tests to focusing more on weather forecasting, planning, and terrain selection. So whether or not you should retake may depend on how long ago it was.
2) In my search for courses I have noticed that several places offer level 1 refresher courses. One being the Outdoor Adventure Club out of Lassen National Forest. This could be a good option, they are usually cheaper and look like a more concise curriculum.
3) He said if your in this similar situation trying to choose what type of course to take to shoot AIARE and email and ask. This is probably your best option. email@example.com