The idea that you cannot refreeze defrosted food is a myth. Any food—even meat—can be refrozen, as long as it hasn’t lingered on the counter for over two hours or spent too many days in the fridge.
Keep your freezer full, but not jam-packed. A full freezer is more energy-efficient than an empty one, but air needs to circulate. As with your refrigerator, keep the air vents unblocked.