Global variable

I have looked and do not see what i am trying to do. I am trying to restart a failed print at the level it failed which is at 106mm on the Z axes. Without having to change every 10,000 lines of G1 ZXXXX is there a global command i could use to start G1 at Z.250 and increment .3 every next Z count? This my first time using G Codes.
Would i be able to use like a G90 -106 at the start.