Brian Carroll does a nice job in addressing this topic in his eBook, Eight Critical Success Factors for Lead Generation:

“…buyers…clearly choose the sales person who has not only been a resource but who has also developed an ongoing relationship with them, regardless of their timing to buy.”

What are you doing to be an ongoing resource to your target customer? Are you telling them when rates are changing? What the latest Fed news means? When their ARM is about to reset?

Call your past clients when they need you not just when you need them.