Save_game is for when you need to exit the game and come back in a new game. If you use global vars they will not be reset when a new level is loaded.

from the manual "The current level is closed, the cache holding level entity files is purged. All current entities in the old level are removed, thus all entity pointers referring to them can't be used anymore."

Darkinferno knows what he's talking about, go his route.

Further, look at how your levels are set up, do you have the player model already in the level at the starting position but the reload level is at a different position? If so it is better to create the player with script along with his position, along with anything else for that level that is not always the same.