No, purchasers of Lance Armstrong's books do not deserve a refund. There is no guarantee of truth in an autobiography. It is up to the reader to draw their own conclusions about the believability of the writer's story. It should come as no surprise that a celebrity would be anything less than 100% honest in an autobiography.
Humans can chose to believe anything that they want. If they have been mislead by false information, it does not constitute a reason for refunding as the organization involved in publishing the work were also believing what the readers were being lead to believe. So it isn't as if they did it on purpose. Schools lie to children, do children deserve a refund?
Most of the people who bought Lance Armstrong's book were probably inspired by him and the story he told. It would seem to me to be quite complicated for him to issue refunds. It's clear that these people are owed an "emotional" refund, a clear admission that he knew he was lying and didn't care about the people his story inspired. In the end, they got more of a story than they paid for, and a sharp lesson about personal integrity. Instead of refunds, he should donate the entire proceeds of that book to cancer research.
The people that decided to purchase Armstrong's books before they knew he was cheating do not deserve a refund. Nobody forced them to buy those books and they should not get a refund. Most people knew Armstrong was cheating and if they chose to ignore the obvious facts then that is their problem.