Once you have started a verse it comes up for review at increasingly spread apart increments. However if you push the see sooner button, you can review it more often. You can also push the practice button to solidify it better in your mind.
I hardly ever actually review my verses, because it takes too long. I almost always just hit the practice button. You don't get points, but my goal is to learn verses, not get achievements. They're nice to earn though. :)