Defending the Bundesliga title is the main target of the Leverkusen team and I see it as very possible for them to do, because the strength of the team and also their rival Bayern Munich are still in repair to rise which has no guarantee to be able to exceed last season's strength.
Defending the title now will be something they will want to go for this coming season but it will be difficult for them to do so because most teams are now preparing and signing players to help improve their squad but Bayern Leverkusen have not really made any significant signing so far. Using the same players over again for another season will be difficult to give them same glory, they can at least try their best but I don’t think it will be easy for them, some players might be fatigued which could be as a result of last season performance while participating in the champions league can also contribute to demoralizing them especially when they lose matches in the champions league.