The Foxes host Porto in the Champions League this week.
Simpson said: “We have to go again. We have a massive game, our first in the Champions League at home and we will have to turn it around.
“It probably helps having a game so soon, you have to focus on that, rather than concentrate on this for the rest of the week.
“It will all be about Porto. It will be a special night, a big night for everyone.
“Facing a team like Porto means we have got to get this result out of our heads and we have to get ready for that.
“I am pretty sure we will be ready for that next challenge, with the players that we have."