Can a Fuel Stabilizer (Sta-bil) be used more than once to prolong a fuel's life?

1 gallon of "Sta-bil" will treat 325 gallons of gas for 2 years. It prevents the gas from gumming up, and keeps it clean. My question is, after 2 years could you add another gallon of Sta-Bil to keep the gasoline clean for another 2 years? Thanks.