Why Japan was unlikely to accept another unequal treaty

Could anything have persuaded Japan to sign a second naval treaty?

Only equality with Britain and the United States was likely to keep Japan in, and that was politically unacceptable to the other powers.

Japan wanted to leave the treaty system. Keeping it inside would require equality with Britain and the United States rather than another limited ratio. That concession would be politically explosive in both Western countries and would transform the naval balance the agreements were designed to regulate. The treaty failed over incompatible political requirements rather than technical disputes over individual ships.