Leverkusen focusing on Bundesliga is an opportunity for to strengthen their performance and again prepare for the next season. Despite their less schedule I still don't believe they can claim back their champion again because bayern Munich have taken over the position and I don't see anything that can stop them from winning the title this season. Bayern Munich eliminated Leverkusen from champions league is also an indication that Leverkusen can do anything to overcome bayern Munich in times of Bundesliga title. I think what they have left in to maintain their position to finish as the best runners-up of the season. Bundesliga teams still have ten matches to play before the season end, so with this I will still be expecting more changes on the table.
Since Bayern is going on with their UCL title chance, that means Bayern will play at least two more games, and possibly four more games too by the looks of it, or what is expected. That means, Leverkusen has one job this season, just win every single game left. If they can win every single game, there is a possibility of Bayern Munich being too tired from UCL games and lose some points, which is quite possible.
However, if Bayern doesn't lose that many points, then there is nothing Leverkusen can do anyways. As long as Leverkusen wins every game left, I am sure that they are going to be the winners of the league, I have no doubt in my mind that Bayern will lose at least 6 more points, maybe even more. If Leverkusen loses points, then it would be their own fault.