Hey there!!
First off, I feel you. In English Advanced for prelim, I felt as though I put in way more effort into the subject than my friends and STILL was ranking exponentially below them. What was more even more embarrassing, was that while they were hating on how horrendous the subject was, I actually liked it. Yet, I managed to JUST make the cutoff for Advanced in year 12 - our school forces the bottom half of the prelim cohort into Standard. It seriously sucks expending so much effort into something and your results not be reflective of it, I get it.
The important thing though, is to focus on your weaknesses. For me, exam technique is always what compromises my marks (specifically time management in exam conditions) - but for you, it might be formulating a cohesive and sophisticated argument itself. I worked my ass off in year 11 despite my shortcomings, and now, I'm ranked 2nd out of 40 students for Advanced with consistent marks of 90 in all assessments thus far. I cannot stress to you enough how important it is to hand in drafts BEFORE the assessment date. I'm quite fortunate in this regard as my school's English faculty is blessed with extremely competent teachers and my one happens to be the head and the best, but even if this is not the case for you, their feedback is absolutely invaluable!! There is no way I would've even imagined achieving marks this high back in year 11 - when I thought it was a lost cause - were it not for the support, expertise and mentorship of my English teacher. It is all literally hard work, and insurmountable levels of drafts, emails, questions etc. I got 60% for creative writing - my absolute weakness - in prelim, but I attained a mark of 93% in my AOS creative for discovery in year 12. That was, after a debilitating back and forth drafting process with my teacher, which involved probably 5-8 emails hahaha. I don't even exactly remember, but it was definitely a LOT more than usual.
As for forming solid arguments, I prepared for Mod A (my half yearly) by not just writing one essay and constantly refining that throughout the term like my peers did, but writing LOTS in the 2 weeks before the exam. At this time, generally I am not really studying - all I'm doing is refining my exam technique. After studying the weeks before this point though, I usually know my texts so well that I'm able to quote from any part of the text as required, with a bank of ideas/themes that I would oscillate between depending on their pertinence to the question at hand. In my study, it is always absolutely imperative for me to immerse myself in the contextual influences of the text. Not just the general, obvious links that are established in class, but more parochial ones that may help you come up with a unique argument. So essentially, it is crucial to have a comprehensive personal understanding of the texts beyond your teacher's interpretation, I suppose is what I'm getting at.
Generally, I never write the same exact essay each time when I'm practising because each question requires differing levels of nuance and I always want to ensure I give the marker the impression that I wrote a well articulated essay that nailed the question, not just one I'd regurgitated onto paper. Particularly for this module (and all of the ones in paper 2 really), I'd advise against responses memorised verbatim because the questions tend to be quite specific. However, if this works for you, then so be it! I just personally think it's risky to commit that much to a generic response because it may subconsciously incline you to prioritise using it in the exam over actually tackling the question you're given, if that makes sense.
I hope this helps you, even if it's a little bit!! I think for me it's much easier because I'm one of the rare people that actually enjoy English (absolutely hate maths though HAHA), but if you even have a glimmer of passion of subject - pursue it! It will motivate you to actually work hard on it. Seek out your errors and work on them, it pays off.