If you didn't receive an offer it will be because your Australian Tertiary Admission Rank (ATAR) was not high enough for any of the programs you applied for ANU.
ANU considers your ATAR or equivalent as well as any other tertiary studies that you may have undertaken.
Applications which have been declined cannot be reconsidered, but you can improve your chances of success with any future applications by obtaining a qualification from another institution, exploring other pathways such as bridging courses or by applying for special consideration.
ANU does not count previous applications against you when reapplying. Every application is considered on its own merit.