Hacker News is designed under the assumption that the quality of a discussion decreases and the likelihood of arguments/flamewars increases over time, and as the ratio of comments to upvotes increases.

If you aren't willing to to put in the effort of checking for responses to your comments, chances are you have nothing of value to contribute. That it takes more effort to do so over time is a feature, not a bug.

Just do what most people here do and cease to care about any conversation once if falls off your threads page.