Here is how it works from what I read:
1.) Get six points during classification period, you move up.
2.) Get a total of 2 points during the next classification period, you stay up.
So basically, if you were moved up and then win sectionals in the next two years of the next period until the end of time the school will never drop down.
Cathedral is a pretty good example. Still up in 5A even though they have not won state in several years. They are currently at 1 point and will win sectionals for sure. (Probably 5A state champion.)