Move all files from your project folder to some folder on desktop
rename the files in recently created desktop folder
delete all entries from info-plist file for icons
start assigning icons again by dragging onto Xcode window at appropriate places.
When you create icons for iphone, xcode automatically assigns those icons to ipad.
DO NOT DELETE THE ENTRIES IN IPAD SECTION. INSTEAD, DRAG IN THE IPAD RELATED ICONS TO REPLACE THE OLD ONES. Rememeber, this is important.