Thanks for the commendation.
I think the longer and the more substantial the review, the more the author may feel compelled to reply. Like in my reply to your (very kind) review of my story, I thought it would have looked a little strange if I had dwelled on the historical aspect, only because you briefly mentioned it as one thing you liked...
Anyway, to answer your question, I think you know that you can always edit/extend your (one) review, even though you can't post a second on the same story.
But that's another reason why an author should reply to reviews, IMO -- once he has done so, he has acknowledged the comments, and the reviewer can edit his first review to react on new aspects which might occur once the story's updated -- if he wants to. Just as well, the author can adjust his reply...