For me, the hardest thing with learning a new language is immersion. I can study grammar, read books and use Duolingo all day long, but in the end it comes down to "living" it.
pretty sure many airlines have apps that let you book a flight! Joking aside, though, there are sometimes alternatives. The most obvious is "study it at a college, not at home", but that can be prohibitively expensive, so an alternative is "volunteer at your local Japanese cultural center". And for at least the writing part, 2ch (not to be confused with 4chan) is still a very popular IRC network: find some channels, hang out in them, and start contributing to conversations. It's a great way to get your brain to exercise its Japanese modalities, even if you don't improve your pronunciations that way.
I wish there was an app for that.