As with any eliquid, keep in a cool place and they should last a while.
Meanwhile, if they are soft-caps (like Vapor4Life) and you can pop the cap see inside for adding juice (or for removing any seals if you want to fill a different way), you could try spinning out the current juice from a few of them then refilling with some compatible lower flavor. I need to do the same thing - I started on 18mg and have stepped down my nic twice and I need to empty a bunch of cartos.
Search Youtube for Reverse Taryn Spin to see how to get juice out. I do not use the filling method show in there.