Organizing my Classroom Library

I have decided to organize my classroom library based on level of reading difficulty. However, I realized that it takes a really long time to do this!
First, I have to go to this website: http://www.arbookfind.com/default.aspx
Then, I actually have to type in the book and write the book level on the inside flap. Instead of doing all this work, I think I'm going to research if doing this is actually worth it!