You can! Just go to Products on the Shopify Dashboard and under the Variants section add your new options. Now scroll to the top of the Products page and click "More Options" to select the Lulu xPress App. You'll see all Product Variants available for connecting, including the one you just added. Click "Configure" and you'll be guided through the file upload process.

According to Shopify documentation, a Product can have up to 100 Variants.