No sorry, you can't
A manual work-around is to use your ftp program to save the following:
- .../administrator/components/com_jreprettypdf/jre_config.php file
- .../administrator/components/com_jreprettypdf/assets directory
Then uninstall PrettyPDF, install the new version and:
- overwrite the assets directory with the old content
- download the new jre_config.php (make backup) and edit the file:
- Overwrite the beginning with the contents of the old jre_config.php as all new entries are added at the end of the config file.
- Now upload the new jre_config.php file back to your site.
This should result in a working PrettyPDF with the old settings retained!