So you have an Amazon Kindle Fire running software version 6.3 and you want to have the latest security features, parental controls and other updates that come with 6.3.1. But your tablet is rooted — and you don’t want to lose root access.
What to do?
Actually it turns out there are two options. You can just let your Kindle download and install the update automatically and then follow our guide for rooting the tablet again.
Or you can install a custom update that only adds the new features from software version 6.3.1.
Xda-developers forum member nfinitefx45 has put together an update.zip file that only contains files in Kindle Fire 6.3.1 that are different from version 6.3.
That means you can flash the update using TWRP or ClockworkMod to upgrade from Kindle Fire 6.3 without losing root access or your custom recovery. The software is pre-rooted and installs busybox and su on your tablet.
The update doesn’t format your device or wipe any data, but nfinitefx45 does recommend wiping your cache and dalvik cache partitions after installing the update.
You can find more details at the download link at the xda-developers forum.