I am not sure what you are asking. What to send them to get them to reply? Do you mean they are not submitting their info to search? If, so chances are they went to another site that doesn't require them to submit their info.
I let them search but grab get their info other ways
1. Save search criteria (obvious)
2. Save Listing (Obvious)
3. E-mail me the Listing in a PDF file (Obvious)
4. Compare Homes: allows them to view properties they have saved side by side so that they can bring up their favorites and compare what home has what
5. Schedule a showing: they submit their info, click on the calendar for the date and submit the time when they want to see it
6. Contact me about a listing (obvious)
7. Free Home updates
The back end of it, I can see what they are saving, comparing or searching for. When talking to them through e-mail or phone I'll mention a property that is getting a lot of attention..I hear agents talking about it around the office....shocker it happens to be one of their saved favorites. I have no clue if it is getting attention or not but they have it as one of their favorites so they get more motivated to see it before somebody buys it.