Must be more contributors.
Absolutely..., no doubt about it...
No, it's that Conservapedia has an unabashed social/political agenda -- spreading the Conservative point of view. It doesn't pretend to be neutral (as Wikipedia does).
As long as it advertises itself with a name and agenda that clearly says, "We're biased in THIS direction", they'll only have a fraction of Conservatives as contributors (those who wish to publicly associate themselves with a conservative political cause), and nobody from elsewhere on the political spectrum.
Personally I'd consider a name change to be the first and most obviously necessary course of action, if they're interested in getting more contributors.