This thread pretty much goes through it, if you want to know peoples ideas and all the perils/ advantages of repeating -
http://vcenotes.com/forum/index.php/topic,28277.0.htmlGenerally theres not many actual disadvantages to repeating, emotional/cbf/i hate this VCE hell/my mates will be out getting wasted in uni comes into play into that decision though.
Your score can't actually get any lower, that is a guarantee.
It will raise but what if it doesnt raise up to what you need? Theres where the trouble is.
If it doesn't get as high as you need, you've basically spent another year in year 12 for nothing.
If you think its the best idea and you are fairly certain you can get to the required score realistically, then i think you should do it. (Eg. If someone got 60 first time around, it'd be quiet a jump for them to get 98 second time... if you got 96 and needed 98, repeating would probably work)
However, the other option of moving onto uni is a better one i reckon.