Refilling a helium tank is simply a matter of locating a gas company and taking the tank to the facility for a charge.
Check the telephone directory yellow pages for industrial or commercial gas distributors, especially cylinder or bulk retailers.
Contact party-supply retailers online or find them in the telephone directory. Most party-supply retailers rent or sell helium tanks and can refill them.
Call a medical-supply company that specializes in oxygen tanks. Many carry other types of pressurized gas, including helium.
Ask a florist if the shop stocks helium. Many florists deliver helium-filled balloons to accompany floral arrangements and get-well gifts, and so they keep helium on hand.
Contact a special-events catering company. Many carry helium tanks for parties.
Buy a pre-filled helium tank at a large retail store if all efforts to locate a helium distributor are unsuccessful. Most big-box chain stores sell disposable helium tanks with a supply of balloons for children's parties.