Couple way...like what Bilz said...either have several smaller paying sites, or a couple of huge paying sites. If you're making 1.63 in 28 days, figure out what your daily traffic is to the site, then see how you can increase that traffic.
there are many things you need to keep in your mind. 1. Traffic 2. Placement of the ads. 3. Making ads more prominent. 4. Content of your site. 5. High pay keywords relevant text. and more.... lol
Check out my website: http://www.MontyOnline.Info It's designed to earn through Adsense. I am making $5 - $8 a day, with this website. If you want your own website like this that earns you $100s a mth, ask me/msg me/e-mail me.
There's a shortcut to make 10K a month if you have 120K to buy a couple of huge developed sites. If you want 1K/month then you'll need only 12K of capital. Check DP's Buy & Sell forum and http://www.sitepoint.com/marketplace/viewcategory.php?categoryid=1
Work harder and be patient. Someone that makes $1000+ a month isn't just kickin' it and letting the dough roll in. They worked hard to get where they (and their sites) are and they continue to work hard once they hit the $1K mark. There is no specific formula to make $1K+ in adsense revenue, if there was, everyone would be doing it a million times over and we would all be billionaires . Unfortunately, it doesn't work that way ...