Slot concedes he struggles to manage a big squad and would prefer to reduce numbers.
Asked about transfers as champions, he told BBC Sport: "I think another question is: 'Does a player that doesn't play that much want to stay at a club where he's not playing that much?'
"I always say that to be on the bench for one season is already difficult - to not play a lot two seasons in a row is almost impossible, so it's not only what I want, it's also what the player wants."
Rivals will strengthen
Slot also said: "(Manchester) City will probably strengthen the squad again. If the rumours are correct, Arsenal is planning the same, so it would be stupid if we are not looking at trying to strengthen the squad as well," he said.
"Again, I've said it many times, it's not that easy because this team has already won the league.
"So to find players that can strengthen us - that might not be that difficult - because there are certain players in the world where I think, 'if they would come, it would be nice'.
"But they're also playing at clubs where they don't want to leave. So there are not many that can strengthen us, but the few that are out there, we will try to get them.
"At this moment of time we're not sure if that's possible."