No, it doesn't; the cap applies only to new H-1Bs. You can extend your H-1B for one more term of 3 years. If you apply for a GC in those 3 years (if you haven't already) and reach a certain stage of the processing, you can get extensions past the 6 years. If you do not apply for a GC, you will have to leave the country after 6 years.