You can destroy the buttons on start of the layout.
And when the player die, make an event that create the buttons on the middle of the screen.
I'm sorry i can't open your capx, there are plugin that i don't have.
I created a sprite that serves as a reference point, and let the RESTART and EXIT buttons off the screen, when "Life = 0", these buttons go to "same position of another object = buttons". Seems to be working well.
Thanks for helping me.