I see the problem, that is why I have hesitated to upgrade more than I absolutely have to.
But BleachBit - if I understand it right - cannot do anything with "real" upgrades, that is, upgrades where new files are actually used. Even without unnecessary upgrades, my persistent image (4GB) gets full, and i plan to do a remastering to be able to free up most of the persistent image and upgrade packages at once.