Printrbot Simple Metal: Auto leveling probe
I’m very happy with this new function. 
Rarely but sometime I still have to reset the Z-height. By now I did this with a connected notebook (M212 Z-0.XXX; M500).
Is there another way to do this?
Octoprint would help you untether.
How are you printing right now? Are you using a microsd card? You could load up a .gcode file with just that 1 line onto that card and run it, but that seems to be a bit of a hassle.
Go buy yourself a Raspberry Pi2 computer, a micro sd card, a cheap webcam, a tiny usb wifi and a micro usb charger. Download OctoPi and write it to the sd card. Put it all together and you have a wireless Web 3d print server. Get with me if you need help.
We are hoping to free up enough code space in marlin to put a calibration wizard in the firmware for use with an oled (or LCD) screen. That pesky z calibration is our #1 ease of use need.
@raykholo I’m using a SDCard. But without feedback where actually the Z-axis is, I cannot alter this value.
Yes, octoprint could work to, but it is at the moment not availlable.
@Rob_Taylor1 That would solve the problem, but I’m using the printers in school and the admin won’t give me access to the WLAN. 
@Brook_Drumm This sounds good! Actually I hoped you are planing such a functionality.
@enhydra Then simply leave out the wifi part.
@enhydra You could use your own wifi router to connect the two. temporarily connect a PC or laptop to it by Ethernet cable to set it up with a user name and password. then unplug and go.