I am a hairstylist. I also have a chi and have had it for years, but I don't use it on a daily basis. I can see that it does now require a few more passes to totally straighten. Babyliss is also very good quality. One reason flat irons don't seem to work as well after the first year is because people use them wrong.
What will help, if she airdries her hair about 75%, then blow drys it with a flat brush. Then, she should take very small and thin sections of hair. Spray each section with a heat protectant, such as Paul Mitchell's Seal and Shine. Not only does it help protect the hair from getting fried as quickly, but it also helps the flattening occur faster and has more longevity throughout the day. So, she is not needing to do constant repeat passes on sections of hair, thus damaging hair faster and wearing out the iron faster.