Lets say i spend 12 mana on some creature (casting cost and enchantements). I attacked first and after its activation, i cast sanctuary. Now my heavy creature is safe, my oponent need to target something else.
I think you are mistaken. When you attack with a creature it makes it inactive. If you reveal Sanctuary afterwards you will remove an inactive creature from the board. Since Dissipate token is removed during Upkeep Phase which is after Reset Phase, on your next turn the creature you bring back will be still inactive and will not be able to attack again. Correct me if I'm wrong.
As far as I know, unless the card says otherwise, creatures teleported out of the arena still reset their action markers. They're not in a zone anymore, but they're still creatures with activations, damage, etc.