I used KDE to resize my Knoppix 3.2 persistent home. Here's the process:
Copy your personal files from the knoppix home to a folder on a hard drive mounted read/write.
Reboot Knoppix without mounting your Knoppix home (no home=scan entry).
Unmount the hard drive you will use for the persistent home.
Go to kmenu, knopppix, configure, and make a persistent home of the new size you want.
Knoppix will make a new sized home over your old home. Be patient, it can take a while.
When the question about encryption comes up, it's done.
Reboot with mounting of the Knoppix home; and the new space should be there.
Go to kmenu, system, info center, storage devices to check the size and free space.