My rate of improvement in Japanese really picked up after starting spaced repetition. I use an app called "Nihongo", which is for Japanese only, but I think Duolingo has German.
That's something I did/do with English. I usually listen to podcasts while going to work (about 1h commute) and it's kinda difficult sometimes to "hear" what it's playing. I mean, I get distracted and suddenly I have no idea what the podcast is about. But I guess that's part of the "passive" exposure.
I suggest supplementing active practice with passive exposure (switch to music with German lyrics, stop watching tv and movies not in German).