I don't have a TF in front of me, but I think this is because when you clear the loop the looper goes to 1/4, 1/2, 1x, or 2x options only.  It actually has a different menu.  When you load a non looper preset and load a looper preset again, it clears the loop, and I guess it's resetting this value.  I can see why this would be frustrating, I'll see if we can address this for the next release.

Dan