You just might want to look up Gamblers Anonymous in your area. If you can't find them, call AA instead and see if they know of anyone in the area along your lines. You are right to view shoplifting as an addiction and its a whole lot easier to give it up with the support of those who understand. At the very least it may be necessary to create something that takes its place in your life, something constructive that can be done daily. Nature abhors a vacuum and quitting, while a very very good thing, makes something of a vacuum that will wear on you.
I know how addictions are firsthand, although mine was alcoholism, however my dad and sister shoplifted. If you find yourself reaching for straws, barely hanging on by your toenails, think about starting your own group, if necessary in order to gain that kind of support. Contact these folks and see what they have to say about that:
Welcome to CASA - Cleptomaniacs And Shoplifters Anonymous - Support for Kleptomania and Shoplifting
I hope this helps and keep the faith, hazel eyed.