I was also questioning whether I should keep chemistry at the end of year 11 but decided to keep it because it's a prereq for many courses and I wasn't quite sure what I wanted to do. My chemistry results were slightly above average within my cohort (although I did go to highly academic school as well) and at the start of year 12 I was thinking that Chemistry would be one of my bottom 2 subjects.
However, I found the 3/4 topics a lot more interesting than Units 1/2 and because of this put a lot more effort into Chemistry than I did in year 11. By midway through the year, chemistry seemed like it would now be one of my top 4 and I was enjoying it a lot more than in Unit 1/2. In the end, it ended up being the subject with the highest raw study score for me (45) so in hindsight I feel like I definitely made the right decision in keeping Chemistry.
If you're not sure what you want to do in Uni, I'd recommend keeping Chemistry to keep your options open but if you're dead set on Arts then I guess you could reconsider. That being said, you might enjoy Units 3/4 Chemistry a lot more like I did and the fact that you've already done Units 1/2 does help - starting a whole new subject without doing Units 1/2 might be a bit more challenging.
Hope this helped and good luck for year 12!