Since electronic cigarettes use an atomizer to vaporize liquid, it stands to reason that the liquid needs to be replenished as it is used up.  This can be done by simply replacing the refill cartridge entirely OR you can place 4 to 5 drops of the eLiquid in the empty cartridge to replenish it.  We now offer e liquid to replenish your used electronic cigarette refill cartridges on a limited basis.  If you decide to try it, let us know your thoughts of the eliquid by emailing us or using our electronic cigarette forum.