You can lead a horse to water...but you can't make it drink.
Some dogs start off on fire then gradually fade away
while others start off slowly but improve with every outing
and some are just downright shirkers
Plug away until you think you've given the dog every chance to improve. then if you are not happy do what you need to do. I certainly wouldn't kennel a dog i wasn't 100% happy with. A dog you ain't happy with will grind you down and make the kennels/hunting an unhappy experience. When that happens then the joy has gone and you'll start to resent the dog. Average is as average does a