How may we try it further?
Claudius knows Polonius has a plan.
He’s seen the machinations of Polonius’ scheming mind and sees the next steps and sees the role he is to play in it. He does not ask, “What should we do about it?” Or “Maybe we should ask Ophelia to requite a little if she wants to if, indeed, the problem is unrequited love.”
He asks how to test the theory. And, of course, Polonius has an experiment in mind. He has already organized the elements, gotten the lab equipment out, set the thing in motion. He’s got the players all lined up and their places reserved behind the curtain. They’re a team, these two – Polonius fed Claudius the set-up, Claudius delivers the reply, then the show proceeds.