Watford boss promises changes
The Hornets lost 6-1 on aggregate, with the second leg at the KC Stadium ending 4-1 in favour of the Tigers, who progress to take on Bristol City in the Wembley final.
Boothroyd told his club's official website: "It's been a difficult season because obviously we started so well.
"I've got some very disappointed players, we're all in it to win it and we started off with that intention at the beginning of the season and to go out in a semi-final is particularly disappointing.
"You reap what you sow, I think we've gone out because we deserved to go out.
"I think that moving forward I've got to look at the squad and what needs adjusting and maybe be a little bit more ruthless than I've been.
"We need to be coming back early and we need perhaps to shift one or two people in and out."