No, the law stipulates that you're grandfathered if you continuously have the service. Once you cancel your service (letting it lapse is the same thing) or once you move, you're out of luck. You're then treated as a brand new customer whose DNS eligibility is then dependent on your new address and whether it is covered by HD LIL or can be covered by DNS.
I hate to say it but Vader is right. The law does not take into account if you ever had them granted. It does not matter if you have them at you address and then you shut them off for some reason and decide you want them back. You lose the grandfathered status and have to apply for waivers again. If your market has HD locals then you will not get any waivers unless there is an affiliate missing in your market and then its still not a gurantee that you will get the waiver approved. It soulds like your setup the way it is is as good as you are going to get at this time.