Yes get semester 2! My son just LOVES the stories. He happily does a few lessons a day if there is a story at the end
We do each lesson once only, but he will pick up the iPad and do some review lessons at times. So eventually he will see each lesson twice ( or more? ) but he didn't like doing the same lesson twice in a row.
Also extend your use of LR by downloading more files from the little reader library. There are enough in their to keep you going for ages. Also make some short stories featuring you child, that is bound to become a firm favourite.