is it worth replacing the engine on a 2006 LR3

Look up private party value on your car with kelly blue book. The condition of the rest of the car is going to play a big role in determining your next step so without knowing that it's going to be hard to give you an answer. If the repair is about what the car is worth and it still has the original transmission, body is rough or it needs other major repairs it may not be worth it. Alex