not only do u put it in a global variable, but u can also play with the "for each object", and place individual, global variables, for each object will allow u to only have to do this once. i had to do this with my game cuz i had split levels, and when u entered a dungeoun layout, and came back to the normal game layout the monsters and the bosses would respawn
EDIT: sorry i couldnt help myself, i never stop thinking. u could also put all the coins from one level into a family, so u would have a family for coins in each level, set ALL the coins to be global objects, that would make the ones u destroyed in one layout destroyed in the next. but if u didnt destroy them they would show up in the next, to solve this problem u would set the family of coins for that particular level as the only ones that are visible, and of course u would have to add a second condition to your collision event that says that if u collide or overlap the coin, AND it is visible, then destroy, so on and so forth.