It would already be a republic if the last referendum wasn't nobbled by the government at the time, where the only choice was between the status quo or giving more power to the historically untrusted elected government.

Per https://en.wikipedia.org/wiki/1999_Australian_republic_refer...:

"With republican models of one form or another winning a majority in opinion polls prior to the referendum, it was expected that the republican referendum would pass. However, the question put was for a particular model of republic with a head of state appointed by Parliament. This was opposed by some supporters of a republic, who preferred a directly elected head of state. Some of these, such as Phil Cleary, advocated that republic supporters vote "No" in order that a future referendum could be put on the directly elected model. Some commentators—including the president of the Australian Republican Movement, Malcolm Turnbull—identified this split within the republican camp as a key reason for the referendum's failure."