Updating Views Module Not Working 7.x-3.13 --> 7.x-3.15
I checked Views module versions from 7.x-3.13 to 7.x-3.15 and it seems that there are no changes needed to be applied to the database (the views.install file didn't change between the two versions). I think you need just to override the module directory with the new version and clear all caches.