If you've got time, doing enough repairs to the 'Mech to allow it to hang by an arm and do a controlled drop off the building might work. It'll probably fall when it lands, but from one or two levels lower than being pushed off. If you have a LOT of time, fix the main motive issue in place.
"Controlled demolition" of the building would mean only using "concentrated laser fire" against one wall, so the 'Mech rolls off that side. Three sides of the building intact, so it might only end up needing 2/3 the cost of the entire building to rebuild the destroyed wall, most of the roof, and half of the interiors of the upper floors.
Another problematical recovery situation is with a 'Mech that loses a leg, engine, or gyro while underwater, and you've got a deadline until the air supply runs out for the MechWarrior inside.