Depending which guide you have there are very likely to be updates on the website. I sugges that you log into the website for the guide you have and check if there are, and then just write the addtions into your guide - that will save you money!
I think what Janet meant was depending upon which guidebook you have there may be updates on the website associated with that guidebook, for instance the CSJ publishes updates to its guides on its website.
The only thing that you might need a new guide book for on the Camino Frances is for any diversion (usually due to roadwork) of the route or new refugios. Your old guide will be good for another year.
Yes Nathanael, hopefully William has clarified what I meant. I don't know which guide book you have, but most of them have websites and generally there are additions and updates on those websites (look in the cover of your book for the website). The Confraternity of St James web site has very good updates on it. Likewise, I suspect that it will depend on when people worked on the updates as to whether the detours for road works etc. will be in there - that is, no doubt, a somewhat changing thing. regards, Janet