There have been many threads about "updating" the old Pal Mickey. I think the **final answer** is that as long as he is out of any bags and facing forward as you walk into the park, he should update himself automatically with all the parade, etc., information. The old Pal Mickey CANNOT get information on RIDES that have been added/created since he was born (like Soarin' and Expedition Everest). There is NO FIX for that (it is a memory problem.)
Otherwise, there are a couple of places in the Magic Kingdom that can "update" him for you (where he can get a check-up) by sticking his nose in a machine. Generally, if you have him out as described above, this is really unnecessary unless he is not acting right.
You can do a search and come up with a number of threads on the subject.