Depends if you really want to, and whether you think you're going to be working your butt off or not. In most cases, subjects aren't worth repeating.. but I got a 34 for English last year and so I'm repeating it this year, as I only finished one essay in the exam, and if I refine my time management skills and work on improving my writing further, I will hopefully be able to get a higher score. It's a different case for everyone I guess. I think a text change, in your case, shouldn't be something to warrant you to repeat a whole subject..
Are you doing English as well? If you are, then I suggest don't repeat Lit and just concentrate on your English. If you're not doing English.. I'd have a big re-think. It also depends on what kind of ATAR you need/desire.