I get longer shelf life out of Superglue by storing it in the refridgerator when not in use and by using a simple straight pin as a closure. The screw on plastic caps tend to encourage glue build up in the nozzle area and blockage. The pin will need a pliers removal often but is very effective. In between Builds I use the screw on cap again. As for the storage in the Fridge, make sure it doesn't get used as a garnish or fed to the gold fish! I recently opened a small bottle of "super thin" from the fridge that was labeled 2010, it's just like new.
Cheers,
Lance