Ah, that clarifies the position a bit. Most of the people I encounter studying Japanese online are doing so without constant immersion, so I made an incorrect assumption.
Regarding dictionary lookups, I've found in a lot of cases that the definitions are not redundant, however some of the more difficult words have rather abstract "heady" Japanese definitions that can whiz over one's head in no time. To remedy this, I suggest you buy a copy of the
例解学習国語辞典 ドラえもん版. This dictionary was given to me as a gift and I have found it an invaluable resource when the "Adult" Japanese definition for a given word is too difficult and the English definition too vague. There are also columns with miscellaneous (and often interesting) information, many illustrations and also usage-breakdowns for related words. Additionally, since it is aimed at Elementary-schoolers, the more difficult kanji always appear with furigana.
For looking up words using kanji, digitized text takes away a lot of the problem. If you aren't using your computer and the internet for dictionary lookups, you should definitely consider doing so. JEDict for the Mac, and Wakan/JWPce for the PC are freely available and extremely useful when you don't feel like thumbing through a paper dictionary. Additionally, tools like rikaichan (or simply copy & paste) can get you quick definitions for unknown words. The only thing left to do is to make some kind of memory aid that will force you to review, because most of the time, if you don't review, you
will forget the word.
For kanji itself, you need to shoot for the jouyou, because the JLPT 2 list is, as I'm sure you realize from your daily experience, totally insufficient. There are many methods, each with their own benefits and pitfalls, but if I have a single piece of advice it is to
learn the radicals, and learn them well. This will allow you to search for (and memorize) characters with much less difficulty.
Regarding context, my personal rule is
only look up words you've encountered, in context, in the wild. This means no vocabulary lists unless you make them yourself. Get a magazine, a novel, a newspaper-- and you're bound to find dozens if not hundreds or even thousands of unknown words. I've found it perfectly fine to review these out-of-context, seeing as 9 times out of 10 I remember the context from where I picked the words up. The point is not to use some canned list.
At any rate, it sounds like you're currently in a really challenging spot. I've heard many a tale and daresay I've experienced it myself in at least a small degree. The only solution is to
endure. As long as you can gut it out, you will advance, even though sometimes it will feel like you're getting nowhere. Just ask your fellow students, they're bound to feel similarly. If you're now shooting for JLPT 2-kyuu then you already know quite a bit, so try to remember that when things start to feel hopeless!
