Do you update to the new version just downloading the new version?
if so it should no delete your files, you can add any new file to the ZennoPoster folder and it will not be deleted after update or even uninstalling the software.
Or you bought an upgrade and install new one?
If so then the modules save in old installation path. ..\ZennoLab\ZennoPoster Satndard\Progs\Modules for example.