Update: UniTether is now UniBoot, add the artikushg.yourepo.com source to Cydia, and install the "UniBoot" package. 3uTools has installed it on Phoenix, it works well (Our test iPhone won't lose jailbreak after rebooting).
Yesterday @ArtikusHG released tweak "UniTether" on Reddit that makes a semi-tethered jailbreak semi-untethered. It does not require an exploit, and it's not how all the previous untethers worked.
How does it work?
UniBoot replaces the intrinsic shutdown and reboot functions of iOS with its own highly modified functions.
These modified functions prevent iOS from unpatching the kernel because the device still has battery left.
The user can now restart his device without the need to re-jailbreak.
Essentially, this untetherer will prevent reboots, which, in turn, prevents re-jailbreaking. You can then use your semi-untethered jailbreak like a fully untethered one.
How will that affect my standby?
The device will be losing around 2%-3% more battery in "UniHalt" than in regular shutdown. Not a big loss not to rejailbreak your device every day, I'd say.
What iOS versions will that work on?
9.x - 10.x. No iOS 11, but I have something better for iOS 11 users coming soon. This includes Pangu93 (NwvaStone), yalu102, saigon, h3lix, g0blin, meridian (when it gets Substrate), and extra_recipe (yep, iPhone 7 users :D).
Open source? Paid? Free?
Yep, opensource (on the final version). And yup, free.
Can I see it in action right now?
Yeah, read as below
Will I still be able to reboot my device?
Yep, by holding home + power for 7 seconds.
Compatibility
UniTether supports both 32-bit and 64-bit jailbreak tools on iOS 9-10.3.3. You can use this untetherer if you are running any of the following jailbreak tools :
Pangu (iOS 9.2-9.3.3)
Phoenix(iOS9.3.5)
yalu102 (iOS 10-10.2)
extra_recipe (iOS 10-10.1.1)
Saigon (iOS 10.2.1)
h3lix (iOS 10-10.3.3)
g0blin (iOS 10.3-10.3.3)
Meridian (iOS 10-10.3.3, useful only when it gets a Cydia update)
Warning: The Debian package is untested so use it at your own risk.
How to install UniBoot on jailbreaks without Cydia support?
Open Safari.
Download the Debian package.
Open it with Filza file manager.
Install the tweak.
Respring your device.
It will now replace your shutdown and reboot functions. You can reboot your device by pressing home and sleep buttons together for 7 seconds.
The developer also update beta 1 on his Twitter if you want to try.