Using a wax melter? Did you know that you have to clean your wax melter at least twice a month to get the "gunk" of old waxes off? How?
When the wax is in liquid state (melted), take a cotton ball and dip it into the melter. It will absorb the old wax. Repeat until no wax residue is left.
When the wax melter has cooled, use alcohol wipe to remove wax residue and scent residue.
Now you can reuse!