I just keep refilling the same one bottle per REO, but I usually have at least 4 going at all times. Lately, I have one in my purse, and one glued to my hand permanently with the new rebuildable atty on it that I've fallen in love with. I really never change bottles....I just refill the one in it with the same juice. Sometimes I even add a different juice to an almost-gone bottle....I'm not that picky. It seems like the juice goes so fast that if I don't like my accidental mix, I just vape it anyway and it's gone before I know it.