Our Optical Illusion

Our oldest daughter got her first pair of glasses about this time last year. One year later, her eyes have gotten worse and she needs an upgrade. I was thinking it would make more sense, both financially as well as just in terms of unnecessary waste, to simply have her lenses upgraded. The couple of places I’ve called, though, are telling me it’s cheaper to buy a whole new pair of glasses.

Why is this? And is it true? Do any of you know of any places that will do a lens upgrade for less than an entire new pair? I’m a bit frustrated. We all really like the way her current glasses look on her and would just like to keep the same frames. But I’m not exactly willing to pay more for less in this case either. Thoughts?