I used to be one of those 'weaker' students in listening. In year 11, I would score 20% in listening tests and sacs. Then I started 100% pure Japanese exposure + massive vocab SRS cramming. (no english at all) My listening comprehension shot up like crazy. It's been about 1 month since I started but I did my listening SAC about 2 weeks ago. I reckon, if I did my SAC now, I could have scored even better. At this point, I know about 65% of the vocab on the vocab list provided and planning to finish up on the last 35% over the next 2 weeks.(approx 1500 words)
The next four months will be dedicated to increasing my passive vocabulary even more(hopefully to reach about 5000 words), and build my active vocabulary through output(speaking and writing).
@Fyrefly - output is always meant to be harder than input. The reason why VCE students find listening "harder" than output(writing and speaking) is because output isn't true output. It's actually rote rotate a bunch of lines in response to rote questions and regurgitate them back to the examiner - no actual "on the spot" speaking and confined to a small number of topics. As for writing, hardly any kanji(150), few "grammar patterns"(65), no causative or passive form and also confined to a small number of topics. Also dictionary allowed. 60 minutes for 500ji.
Also people suck at Japanese because resources are limited. Outside, native resources such as news or even anime or drama is too hard for the scope of the course usually in terms of vocabulary or kanji. I think the people who do well in VCE Japanese are those whos ability is beyond the scope of VCE Japanese and are able to make sure of "outside resources".
tl:dr - Massive exposure + massive vocab SRS cramming = ftw. (Also make sure you know your grammar well)