[earthfrog]

Refrigeration may help preserve the vitamins if you also add silica packs to the mixes. Upon removal from the fridge, condensation sets in on the pack's inner walls, which lowers the mix's potency each time you remove it from cold storage. Using a silica pack (found in most vitamin jars) absorbs extra ambient moisture and could slow this process and allow your vitamins to last longer. I am hoping Repashy will start adding this feature to their vitamins as do other vitamin manufacturers.
I am not sure on any official vitamin preservation timetables. It is recommended to replace vitamins within six months, and I'd say that depends on storing them in a cool, dry area (contrasted with not storing them in a warm or humid area).