Adjusting speed in rhythm game

I am working on a DDR-like rhythm game. The speed of the arrows moving up the screen and the distance between them are already defined as arrowSpeed and sTempo, respectively, but say I wanted those values to be different based on the current level/song being played.

How would I accomplish this? If/else statements? Or something else?

If anyone could help me out I’d really appreciate it!

SOURCE:
http://tsuaii.com/dl/hondafoo.fla