I am fluent in German, it was the very first language I learned. I know German, Spanish, and English all like the under-side of my tongue!
But when it comes to a language then yes, your option is basically memorize and talk with people in german and let them correct you.
I'd be more than happy to talk with someone in German, my own german has been weakening since I don't really have anyone to talk to with, but I refuse to forget it! That's another important part. Your will. If you want something, you'll get it. If you don't then don't bother.