While Premier League champions this season, Slot concedes there is regret around their Champions League quarterfinal defeat.
Slot said, “We were in the wrong place in the wrong time, facing Paris Saint-Germain.
"I think at that moment of time, that wasn't our best part of the season, although the home game we played really well. So you could argue if I needed to have rotated a bit more between November and March to be even fresher in that game.
"As we all know, we went out of the cup in Plymouth, and against PSV (in Champions League qualifying) we lost, which wasn't an important game anymore. And I think I made six substitutions against Paris Saint-Germain, where the extra time wasn't our best period of the game.”
Slot also said: “If I look at the way we think about next season and our squad, these are things that are on my mind. I think we can find one or two extra weapons that this team doesn’t have.
"Maybe by using the transfer market. That is what we are trying to achieve. That will make us only stronger.
“That is what we need because we saw (Manchester) City spending £200m in the transfer window. All of them will.”