Epoxy nozzle reamers

[ductape]

The lids on these type of bottles really can't be airtight enough to completely stop the evaporation of solvents or the reaction with oxygen, moisture, etc. My guess is that is what causes the tiny drop left in the nozzle to thicken and create a clog. Storing the product upside-down seems to help slow the process in between use. This may or may not be a useful addition to your idea.
I've had some luck doing this to prolong the shelf life of polyurethane glue, which as you mentioned is less stable than two part adhesives.