I did it today at college actually. I didn't have much sleep that night but i got 13.0 which was the same as last time a couple of months ago. So i guess i've maintained. But to be honest, the bleep test isn't that accurate in measuring maximum fitness but more-so how far you can go balls out and keep going. I always have 13 in my head so once i hear it my body just stops as if to say mission accomplished.