Help with followup script and changing my offer

[Silver A.]

Hi all,

BP community has been extremely helpful and taught me more than I can ever give back. I am writing this since I would not find a script as such from other topics.

Here's the situation: the seller has called me and told me all I need to know about the property. We met and the seller was more than happy to show the property to me. It fits my investment criteria.
I find out that they must sell it in 6 months, but my offer of 70% ARV (minus repairs) is way too low for them for now. We agree to keep in touch if either one of us decides to change ones mind.

When and how should I do a follow up call again?
- so far I have been calling them after 3 weeks and then in a month just to see how they are doing. Usually they are still waiting for better offer, have not listed the property and my price is still too low.

What could I say if I decide to offer then a bit more for the property?

And most of all, some people have written here that they offer a bit less after a month than they originally were willing to pay. A script for that would be much appreciated!