My PS was four paragraphs the first time around. This cycle I took out the weakest one and replaced it with one that detailed what I've been doing this past year, selling my tenacity, all that jazz. I edited the other three so that they flowed into each other smoothly since I changed their order slightly. I received compliments on my PS during my interviews last cycle, so I didn't want to spoil the magic.
As far as secondaries, some of the questions on mine were things like "how should physicians react to patients", "what impact has your family had" and static things like that. I'll give them a once over, but my ideas haven't really changed much. If my answer to any question might be enhanced or altered by something that's happened to me since last cycle I'm going to change it to reflect that, but otherwise I'll probably keep at least the same framework.
My biggest changes will be my MCAT, grades, and letters of rec. Hopefully they will make a big enough statement.