Click on the Chrome menu (triple bars in the upper right, as circled in the screenshot below)
From the menu, select More Tools and click Extensions. Chrome will launch the Extensions window in a new tab.
Check the Developer Mode checkbox in the upper right, then click the button that appears underneath it to Update extensions now.
Look further down on this page to see the updated TreasuryBox version. You can now uncheck Developer Mode and close the Extensions tab.