This plugin removes all data on deletion, however there is a way to delete all data without deleting completely the plugin:

1. Go to WordPress admin area and visit Reactions » General Settings page;
2. Click on Preferences tab;
3. Click on the Delete button near Remove all data label. On multisite installation this option is available only on main site settings;
4. A confirm window will appear, click “Confirm”;

Now all plugin data is deleted, you may start from scratch.