since I'm a product of the computer age... I do this in a MS-Access database!
Have a look at http://www.photocritique.net/g/s?zzig4c-p21162059 for an example athough that one doesn't have any exposure data on it. For print exposure, I record (in the other info column) enlarger, enlargement size, aperture, filter grade, time and any other details that are neccessary. For a straight print it would say M601, 295mm, f8, G1.5, 6secs. I file that page back to back with the contact sheet in a plastic sleeve in a folder (with the negs in a neg sleeve)
Yesterday, I reprinted a print I did in 2001 using my recorded data and it was spot on!