Not a definitive solution, but in the last and most desperate and agonic hours it may help (posted in another forum):
Once a country is reduced to two bases, a new virtual base is spawn. The new base is placed just at the map margings, at the closest point between a map marging and one of the surviving bases (choosen randomly). This new base is really an airborne spawn point that will simulate reinforcements from outside the map, with planes spawning at 250 mph, 5k-15k (also choosen randomly per plane spawning) and leveled (dont try to spawn there with a vehicle ). This spawn point doesnt count for a reset and is deactivated when a third base is recovered.