The tweet lifespan is short, and if you try to make up for that by sending the same tweet over and over, you will get un-followed and your reach will shrink.
But Twitter can still be effective, and here’s how to create a great tweet from Jakob Nielsen: http://www.useit.com/alertbox/twitter-iterations.html
So make your tweets as effective as they can be. Be resolved that their time in the spotlight will be short. And then go on to defining your next tweet.