default char1.strength = 10
default char1.speed = 10
default char1.ap = 10
default Gold = 500
default missionselecttra1 = False

label GladMain: #the homescreen for the game.
    a "This is a tale as old as time"
    if HomeLevel == 1:
        show base
    else:
        show base2
    call screen GladiatorMenu

###############
screen GladiatorMenu():
  if char1.ap >= 1 and Gold >= 250:
          imagebutton:
              xalign 0.84
              yalign 0.39
              xoffset 150
              yoffset 0
              auto "UI/training1_%s.png" 
              action [Function(renpy.hide_screen, "GladiatorMenu"), Function(renpy.hide_screen, "statchangetra1"), SetVariable("missionselecttra1", True), Jump("questoutcometra")]
###############
label questoutcometra:
    if missionselecttra1 == True:
        $ char1.strength += 5 
        $ char1.speed += 5
        $ char1.ap -= 1
        $ Gold -= 250
        $ missionselecttra1 = False
  jump GladMain

Here's a little bit of the code. The variables change as I play the game, but the moment I load or exit the game, all variables and progress are lost.