There is no SongBook 2 application. I have searched on known engines, but there is no information about it. However, there is SongBook application released by LinkSoft which is shareware. This means you can download and use the application but with limited functions or based on a trial for a limited amount of time. Buying it will also remove these limitations and unlock the full potential of the application.
You can check more on the following website: http://linkesoft.com/songbook/