I would probably put electric fencing on top of the original fencing. I would hesitate to use barbwire as I have multiple scars from it (farm kid)
Last fall I found the kids that live behind us hopping over the fence, I told them nicely to come to the door and I would gladly get their ball. Their mother got all huffy about that one, but I knew in the summer I would be getting a large, territorial breed of dog and I was not going to take any chances, thankfully they listened and I have not seen them go over the fence since.
Teagan Westhighland White Terrier
Panzer South African Boerboel Mastiff