Your previous book helped me a lot to pass my Java 6 Programmer Certificate!
Now I am planning to take an upgrade exam.
I am curious if you specially dedicate some chapters in the book to upgrade certificate, for example, to upgrade certificate from Java SE 6 and all prior versions?
Well we didn't do that... so you'll need to study the objectives for the upgrade and the objectives for OCP8 and do that yourself (you can use the handy objectives table in the intro for OCP8 and the online objectives for upgrade for comparison).
For those items NOT on the OCP 8 exam that ARE in the upgrade, you can find those listed in the introduction (there are basically only a handful) and the appendix for more details.