Getting past the intermediate stage of Japanese
I wanted to know how other people got past this stage, because I've found that lately, the rate I learn Japanese has slowed dramatically. To give some background details about my personal situation, I've reached the point where I can communicate in Japanese on a wide variety of topics at close to normal speed without switching into English. The problem for me though, is that my vocabulary is only good enough to allow me to understand those things and understand about 60-70% of more complicated conversations. Or slang, for that matter, because I originally learned 丁寧語 in a classroom setting and had to teach myself more casual forms. I can also only read about 500 kanji, and even with furigana, I can't read something like a novel yet.
My goal is to become fluent, so for those of you who already passed this barrier or are currently working on it, what specific strategies have you found to be useful?