while i'm not familiar with the lost techniques of kempo specifically, usually "lost techniques" really refers to techniques borrowed from other arts then attached to the style in question by way of a new, unverified history.
Hmm, I know that a friend of mine who trained in an offshoot of Parker Kenpo learned some techniques which he was told by his instructor used to be in the EPAK system but were removed. I think one was called "Crashing Cymbols" and was similar in nature to Obscure Sword.
I know that the Kenpo I learned was a hybrid of EPAK and TRACY's, but mostly EPAK, and it contained some techniques which I haven't seen taught in some EPAK schools, including the afformentioned Intellectual Departure.
I also know that in some independent Kenpo schools the instructors have created their own material, which future students may wonder as to the history of and could be thought of as some as "lost" techniques, when in fact they are new inventions.