Yes we will find it difficult to think that someone will bring the same thing later, maybe the answer is three, get better, get worse or stagnate, so Leverkusen has a chance of not experiencing the same thing next season, but we also don't know what next season will be like because all teams see Leverkusen's play in the previous season and they see Leverkusen's defeat and can judge where Leverkusen's shortcomings are, That is the basic key to beating Leverkusen with Leverkusen's strategy in the past season, but maybe xabi Alonso has a new plan to surprise next season in his own way or he can no longer be as competitive as before, especially in the champions league which is basically tighter competition.
Improvements will definitely occur, especially since they will definitely bring in new players who can fill positions which last season still had weaknesses. No matter how good they are this season with no defeats in the Bundesliga and only 1 defeat in all competitions, they still have to evaluate everything, they must not be satisfied with what they have achieved this season, because if that happens then they might decline.
They have a target of retaining the title in the Bundesliga or other domestic leagues, such as the DFB. Therefore they have to improve themselves to be better.
They also have a new challenge in the Champions League, the competition there is very tight and it is definitely not an easy thing, they have to prepare for it as best as possible.