kelpies are often described as what a border collie would be like if given speed. Kelpie-BC cross, I can't imagine the energy level. Such dogs need more than physical exercise-- they need mental work as well. Sounds like the dog needs training, and what better way to give a dog mental work than by training? Training is best done in short sessions scattered throughout the day-- 5minutes here and there throughout the day.
But seriously, I'm an experienced dog person, and I would never take on a kelpieBC cross, I know I couldn't handle it. Such a dog needs to go to home with a demanding job for him-- herding stock, or competitive agility.