Direct Mail(Handwritten Letter) Follow Up?

[Hayes Mercure]

So I've done a first round of handwriting owners of off-market properties that I'm interested in. I plan to do a monthly follow up. For the follow up, I'm not sure what to write. Am I essentially saying the same thing as my initial letter? That I really like the property, I'd love to talk to them about buying it, if they are interested in selling, etc.? Or should it be shorter and more of a "just checking in" type of letter?

Any insight/advice is highly appreciated!