The fastest way to plow through your juices is to "accidentally" knock the bottle over when you're filling a tank or to pull the bottom of your tank filled with undesired juice. Ooops!
I know that refrigerating juices is supposed to prolong the life of the juices, but I also know that most juices have a shelf life of a year or so before the nic starts to degrade. I don't know that I would vape the over two year old ones.
Yeah, I've heard some say it's two years, others one year. However, I was vaping higher nic juice a couple of years ago, so if the nic's degraded there's still gotta be a fair amount in them. I've been vaping some 2-year-old coffee juice for a while, and I haven't been climbing the walls in nic-fits. We'll see how it goes.