for android u need extra .apk for extra (iap) content.
also u can make a full version and enable only the payed "files".
also possible loading files with http commands from web server,
but this will result in trouble with google shop views.
did u use the online apk tool?
are u sure u had zip the media folder again.
or was it possible to save the file at device from app
in domuments at your device (then try delete this file )?
try GetFileExists ( szFile ) and make a version nr. / date in file too. u can print on screen than.
AGK 108 (B)19 : Windows 8.1 Pro 64 Bit : AMD Radeon R7 265