They didn't have a serious plan to do so. In the minds of the Japanese leadership, their strike on Pearl Harbor was meant to be a decisive battle like the Russo-Japanese war; it was meant to be so debilitating that the US would give up before war ever began.

Of course, the idea is in retrospect mad. But the main goal of Japanese expansionism that launched the Pacific war was to secure resources. Once they had secured the resources and destroyed the US Navy, they would be in a good position to finish off China.

Once it became clear that the US would not so easily surrender, the Japanese warplan switched to a "Fortress Pacific" mindset, in which they'd have a defense in depth of islands to harass interdict the Americans.

So expansionism toward Hawaii was never really part of any serious Japanese strategic plan.