I tried keeping some diluted iodophor but noticed after several hours the solution was becoming clearer. I took that to mean it had a relatively short shelf life when diluted. There is some good info out there if you Google "iodophor shelf life" .... The following is sniped from an interview with the General Manager of BTF, Dr. L. Charles Landman. Pretty much confirms my suspicions. I'd just mix a fresh batch each time .... it's cheap insurance.
"Regarding iodophor that has been diluted to a working solution, Dr. Landman explained that there are a number of things that work to degrade the products' efficacy. Chlorine and protein load were the two mentioned first, but Dr. Landman agreed that both sunlight and exposure to the atmosphere may very well be factors. Iodophor is very stable in it's undiluted form, but will begin to degrade, (albeit slowly), once it has been diluted to a working solution. In either case, it is far more stable than chlorine which begins to degrade immediately upon being manufactured. The color of the iodophor solution is a rough guide to it's effectiveness as a sanitizer. If the solution still has its amber color, it is most likely still active. It is recommended that a fresh solution should be mixed when the color fades or after 24 hours."
The entire article by Robert Arguello is at http://www.bayareamashers.org/content/maindocs/iodophor.htm
Bruce