To edit an active goal, log into your 22seven profile and click on the 'GOALS' tab in the menu bar. You'll automatically land on the 'Active' goals tab.
Click on the 'EDIT' button on the goal you'd like to change. You'll have the option to change your goal's name, the total amount you need and its completion date. This will adjust your monthly contribution calculation.
Make sure to click 'SAVE' if you make changes.