One of my favorite things when working with a woman's wardrobe is creating multiple looks from an item they were only wearing one way. You don't always need "more," but sometimes just a different eye about how to wear what you have in fresh ways.
See below for some inspiration about how to wear a summer dress multiple ways. Each set creates a different look by switching out the layers, accessories and shoes.
For the third look, you can recreate this with various shirts. For example, you could similarly tie a white button-down or a chambray button-down at the waist depending on what you already own and what you like.