Initiation is supposed to be exciting. But challenging?
My suggestion is to make pledgeship more challenging. Not by hazing though!
Have pop quizzes to see if they can remember the creed. Think of new ways that they can remember your sorority's history. You can also have a requirement that the participate in a philanthropy project or a school activity outside the sorority or have a certain GPA before initiation. Before I was initiated, we had to do all three before we were initiated.