First, you need to think twice if the effort is worth the investment.
Somehow, I believe that you've already passed this stage, so I will not discuss it in any more details. In learning language, you need to understand what exactly you need. Some people need to master the oral language. For the others, very basic speaking skills are sufficient, while the written language is more important. A wonderful oral interpreter may be a mediocre translator of written texts and vice versa. Different aspects require different training. I think that only the first two years of language studying are similar for all learners, starting from the third year or so you'd better start to specialize in what you feel is more important.
Secondly, you need to stay creative and always search for better ways to learn language. Most of us (me included) spend a lot of time on things that are of almost no use and will most likely be forgotten after the exams. I also believe that most of us are too lazy to revise what we have learned previously and actually start to use this material. Instead, we choose to learn something 'new', and effectively end up having learned a lot, but being able to say or write very little.
Last, you need more real-world language. If spoken language is important for you, find a chance to speak to Russians. If written language is what you need, read more of the modern media, classical and modern literature. Try to find someone who would explain the more difficult parts to you. Learn what an average Russian might have read during his school days, and try to read at least part of it.
I wish I also could study more systematically. And I think, I would have really benefited if someone had given me such an advice when I was just starting to learn Chinese.