Hade a 17h print fail on me today only 2h left!! 
the print failed in a “good” way (clean stop / no spaghetti). Is it possible to restart it even if I have auto bed leveling and a z probe (cant cero z with print on bed). I have only klicked cancel in octoprint maby the z is still correct? Will the auto bed work if I restart without start g code?
Cura has a nice feature where you can cut the bottom off an object. measure the height that was printed and have cura cut that much off the print reprint and stick it to the top of your print.
That is one option. But I think the part will get stronger if I can continue it. Its hard to glue infill (i can be wrong).
If you can find the exact layer it stopped at, you might be able to manually modify the gcode file, remove anything up to that layer (that got already printed), then it could work. But it’s tricky and could fail just as easily.
The bottom layer on the new print will be solid so the infill will stick to a solid layer. Did a skull like that about a year ago glued with superglue and it stuck like anything.