You don't have to clean install.
You can flash this file in recoveryhttps://www.androidfilehost.com/?fid=95916177934527961
Download SQLite Editor from playstore.
Scroll down until you see Settings.db.
Under settings.db click on secure.
Scroll down to "themeConfig". Click on it and then click on the pencil (edit) icon.
Select all text in the value section and delete it.
This will restore the default theme and once you apply your preferred theme and reboot, your drawer will be themed.