Or see if your uni offers any courses/program that will allow you to do a year of general study at uni and get a uai at the end of it. I know Newcastle Uni has NewStep a 1 year general course, a fair few people from my year went and did that and know will be off to uni next year.
Otherwise there is of course Tafe. Again Newcastle uni was offering anyone who had completed Cert IV+ entry into uni on a certain number of courses. Of course this would differ from uni to uni, I think Newcastle is just trying to boast numbers as I know this year they had spare places for quiet a number of courses/degrees.
There is also redoing the hsc again either at school or tafe. You don't have to do every course again just the ones you think you can improve on.