A couple of months ago, I heard from someone who had taken my PPC class at UCSD Extension five years ago. He had been receiving my email newsletter over the past five years. And even though we had not spoken in five years, he was willing to refer two potential clients to me when the opportunity arose.
That is the power of ongoing communication!
So, if you are not doing a regular newsletter or other form of ongoing communication, I strongly recommend that you initiate one