Comments bump post

Sorry I don’t know of that exactly, but, you could get a Recent Comments plugin (such as one called, “Recent Comments”).

It lets you show a loop of posts that had recent comments. Example, you set it to pull in the 10 posts with the most recent comments, and for each of those posts it could display (for example): Post title, Post excerpt, Commenter’s name, Link to the post, Link to the comment.

So you can basically set it up to show whatever stuff from the posts with recent comments that you want.

So it’s a similar idea of what you want. But it will not re-date and re-publish the original post