If a person is the sum of all his experiences, a clone is no more the person whose genetic structure he shares than he is a photograph or sculpture of that person. To transform a clone into that person, a way needs to be found to make the clone's mind identical to the person's mind.
In many campaign worlds, the person involved makes a recording of his brain pattern and transfers the pattern to the clone while it is still in a formative stage. (Exactly how this is accomplished varies widely from setting to setting.) The clone awakens with all the memories and experiences of the person up to the point of the recording-anything that happens to the person after the recording is not part of the pattern.
In settings where clones are kept as organic life insurance, people periodically record their brain patterns so their clone has the most up to date memory possible. In settings such as this, it is possible to use technology in unusual ways. One could imprint the mind of a clone with the brain pattern of another person. Alternatively, an elderly person on his deathbed could have his brain pattern recorded and, after he passes away, implanted on a clone of himself as a young man.