Select bibisco from your products:
You will land on a page where you can download the new version of bibisco:
The first time you purchased bibisco you received an email like this (if you can't find it check the spam folder):
Press the button View content; the button takes you to a page where you can download the new version of the application:
Install the new version using these instructions.
When bibisco starts, select the project directory you were working on as a project directory (Where is my projects directory?).