No great non-surgical options for a double chin

Once you have lost weight, your skin needs to shrink if it can.  If it does not have the elasticity to shrink away the excess, it will look loose and lax.  Once this has occurred, the only way to improve it substantially is with surgery.  

Thousands of dollars have been spent by patients pursuing non-surgical tretments like Thermage and most are left disappointed with minimal to no correction.  Bottom line is that once you have excess skin, surgery is the only way to tighten it up.