If downloading the current hotfix did not solve the "Leap Motion Controller" plugin issue for you we sadly have to have you get a full redownload.
Our user Buggl couldn't fix the issue by download the update itself, but by deleting his local game content and then redownloading the game easily.
In order to do this, if this issue affects you: right click RUMP! in your library and directly choose "Delete Local Content" or go to the game properties and choose to delete the contents from there. Redownload a fresh copy and you should be as fine as Buggl is now.
This download ain't much bigger than the patch, since neither the Engine nor the Steam Pipe could detect our rather small changes, but created a rather unusual large update. Sorry for the size to low bandwith users.