Yeh, if you didn't get anything you want check the cut-off list and those marked with (V) still have spaces. So put the courses down with vaccancies or with a lower cut-off than your uai(hopefully someone changes their pref's or rejects what they got). So yeh just change your prefs.
http://www.uac.edu.au/pdf/2008_uai_coffs_csp_main.pdf
http://www.uac.edu.au/pdf/2008_uai_coffs_dfee_main.pdf
Also: " If I receive a Main Round offer, can I accept my offer and also change preferences for consideration in the Late and Final rounds?
Yes, UAC advises you to accept your Main Round offer. You can then also submit a change of preference for the Late and Final rounds. You do not jeopardise your chances of receiving another offer by accepting your Main Round offer.
If you receive an offer in one round and accept it, and then receive an offer in a later round, you can choose either to:
keep your previous offer and not accept your new offer or
withdraw from your previous offer and accept your new offer.
You do not need to change your preferences if you want to be considered for preferences higher than your offer - ie. if you receive a Main Round offer for your third preference, you will automatically be considered for your first and second preferences again in the Late and Final rounds if those courses have vacancies.
Do not assume you will receive an offer in the Late and Final rounds - it will depend on whether there are vacancies in the course/s. Also, the cut-off for a course in the Late and Final rounds could be less than, greater than, or the same as the cut-off in the Main Round."