Android 5.1.1 OTA on rooted device without losing data

Hi all,

I have Nexus 5 Android version 5.1 (LMY47I), rooted, unlocked bootloader and TWRP.
As we all know OTA doesn't work with rooted devices...

Is there a way to update to Android 5.1.1 flashing the OTA zip file without losing data (apps data, pics, vids, etc) ?

By the way which should be the right file? LMY48B or LMY48I ?
Whats the difference?

Thank you.