Well well well, the list has been a bit slow. All those IUF folk have
been blabbing about important stuff so there has been little time to
write. About pedals though; If you had bought GOOD parts in the first
place this probably wouldnt have happened. 
If you have quality
stuff, and here’s the important part: If you keep your quality stuff
tight, the cranks usually don’t get stripped. I have found that the
only times that I have broken anything on my cycle, it was a result of
lack of care/knowledge. In short; If you use good parts and keep them
in working order, nothing should break, aside from the usual wear and
tear. To fix your problem, I would buy some new cranks + some new
pedals. It probably is not worth your while to drill out the cranks,
fit them with an adapter, blah blah woof woof. (you get the point).
You might have trouble finding 125 mm or unicycle size cranks at a
bike shop since most kids bikes use a one piece crank, but you could
always call Tom Miller, Unicycle dealer, at (317)-452-2692. Good luck
Karl (you know, the one from Madison)