The only other way I can find around this (other than trying to re-locate the original meshes and recolors the sims' hairs require) is if you load those sims in CAS and give them a new hairstyle, then add them to one of your neighborhoods, and extract them from the game using 
SimPE and the tutorial for 
extracting born in-game sims.  I ran across this problem a lot after I cleaned out my downloads folder, and found that I did something stupid by not paying attention to what I was deleting.  :lol: