MicrostockGroup

I think it might be wise to reshoot some of them, especially if hairstyles and clothing looks dated. 
-DT just had a contest asking for reshoots of good sellers. 
-Rich Legg recently blogged about it.

http://www.leggnet.com/2010/01/changing-styles-revising-my-stock.html

Question is if it's worth competing with yourself? Do you have experience showing that "new" image will actually do better than "old" one? It also depends how search engines are tweaked. Would new image with similar meta data hide old one in search results or not?

Bottom line is if it is a good selling subject and can be shot better than you already did it, somebody else WILL upload competing shots.  If you don't shoot it better you will lose out on sales to someone who did. 

Either you compete with yourself or someone else will

I often get caught up doing similar subjects. Fact is most successful photographers do. You get good at it and develop a range of techniques and supply of props. I can't see the difference in sitting another three business people down at a computer for the 1000th time or reshooting a medical item.