Press '4' to go to the 100th level.
Begin play and hold down either 'SHIFT' key and the 'SPACE BAR'. Now press any of the following keys: '1', '2', '3', and '4'.
http://www.netrover.com/~timt/cheats/k/klax.html (Amiga Plus Extra No. 5/97, 05/1997)