I'm not sure if this will help, but you still have access to Kubuntu from the LMCE GUI.
From there, you also have a Konsole shell you can run and can apt-get components off the repositories.
I have done this on my LMCE Hybrid. As to updates/upgrade of Kubuntu, I would guess it would be this way? I haven't had a need to do that yet.
Hope that helps.