That is unfortunate as there is no quick way to replace such a large portion of the canopy of the tree. I would identify well-placed branches in the area of the lost limbs and train them as best you can in the direction which the lost limbs were growing. You can do this by tying them to stakes to direct them into the void that now exists. Since there is plenty of light in that area, the branches should respond well. Other than fertilizing and watering to ensure vigor, it will unfortunately be some time before the void is filled.