You can submit only one application to UAC Postgraduate.
If you applied for admission in Intakes 1-3 (commencing December 2009-April 2010) you DO NOT need to re-apply for Intakes 4-6 (commencing May-November 2010). Your application will remain valid, so in order to be considered for Intake 4-6 courses all you need to do is change your course choices through Online applicant services.
If you have additional qualifications to be included with your application, go to Online applicant services and select Add/modify study/qualifications.