I don't know of a program that changes the bpm... but if you want to speed up vocals or slow them down, adobe audition (or cool edit) does that... let's say you have something at 80 bpm and you want to make it 85 bpm... you divide 85 by 80... 85/80= 1,0625.... and you speed up the original file at a ratio of 106.25%... If I'm not mistaken, I think you have Cubase... I'm 99% sure that you can do something like that in Cubase

so I don'T think you need to buy anything