Sane has been linked with a move to Bavaria after he started only 21 games in the Premier League for Pep Guardiola's domestic treble-winning side last season.
"Bayern's German players are now very much looking forward to Sane's signing, but we have to wait and see what is going on," Lewandowski told Goal.
"They [Robben and Ribery] are legends, of course their departure is sad.
“But Bayern will also sign more and better replacements. I believe that the winger Bayern will sign in the future will be as good as Robben and Ribery.
"In order to have a good performance next season and to overcome Dortmund, I hope that Bayern can do something in the transfer market this summer."