Since you wont get the broadcast anymore, wouldn't be the best direction for you to try and improve performance on your blurring method, and do it on-the-fly without SD card storage?
The thing is, for the user to change the background, they pretty much have to leave your app (and that you can still notice), and getting down to at most say a second for the blurring when they re-enter your app should still be ok-ish user experience.
Maybe have a look here (if you haven't already), regarding fast image blur on android: