Hi, I bounced into the same problem that my KDE was gone. My simple solution was to build a dummy DEB for ksysguard.
I've placed it on the web for your pleasure: http://www.hugo.weite-welt.com/ksysguard_3.1.3-1_all.deb after installing that deb you can run: apt-get install kdebase and you are a lucky man again. Warning: That package works for me, I won't give any support nor nothing for that. Cheers Leif