After a day or so, look at your previous day's tweets. Take the replies you made and look to see if there are any faves, retweets or replies to those tweets. If not, store in a database the name of the person who you replied to with the the tweet in question. At the end of the month, tally up the usernames you replied to and rank them. Send an email with a report of the replies that went ignored.
The people with the most ignored tweets are ignoring you, so maybe you can spend the energy more usefully. Also, use the data to evaluate which replies got ignored. Maybe those aren't funny, insightful, etc.