Maybe it's been a while since you signed up, or you've made enough progress towards your weight goals to the point where you need new nutrition targets.
The first step is to update your physical profile with your new weight. The quickest way to do this is to click your weight in the navigation sidebar:
This will open up a popup that lets you update your current weight, as well as your weight goal. Once you make those changes, one of the buttons at the bottom of that popup says "Update your nutrition targets based on your new weight goal?" (seen here:)
Click that, and it will show you what changes to your nutrition targets our calculator suggests. The nutrition target changes must be applied to a specific Nutrition Profile, so select which one you want, and then select "Apply nutrition targets".
If you want new meal plans that reflect your new targets, either use the Regenerate Week button, or regenerate individual days with the refresh buttons at the top of each day's plan.