The High Road

What do you suggest one do when the “high road” is closed.  I recently left employment at my three-years-elder sister’s company because of differences in our approaches to business.  While I continue to reach out to her via email at least weekly (e.g., to tell her that I love and miss her, or to send an article that I think she might find valuable), she does not acknowledge me.  Is there ever a time to stop going down that road?    Thank you.