Hi foofighter,
As they say "where there's a will,there's a way". If you put the requisite amount of "smart" work and keep on improving yourself on the different areas,I don't see any reason why you shouldn't be able to improve.
Since as you said that you have plenty of time to prepare, I'd suggest that firstly read as much good text as possible. Read the article from different areas in The Wall Street Journal, The New York Times etc. The quality of articles in these newspapers is quite good and it'd help in making you familiar with complex sentence construction .As a result, you'll be able to tackle RC and CR with more confidence. I think this should also help in SC. By the way, when you do you plan to take the GMAT?