Repackage what you sell and visit them again and again and again. Make a deal with your competitors. Why not go to a competitor and give them a try. They might be able to sell people you were unable to and pay you part of what they make. You do the same for their list of dead prospects.
Society is impatient.
This problem almost killed my business earlier this year. People will not put up with slow delivery. Go nuts with follow-up. It will tell them you value the relationship. If you are in it for the one off sale, you will be hungry and poor in this business.