TWL comes out with new collections and designs each season. If something is out of stock, you can sign up for back in stock email alerts on the product page of the out of stock item.
As a guide, most of our designs are limited runs, so once they are sold out they are gone for good. :(
The best way to stay on top of all the new drops and releases would be to sign up for our newsletter on our homepage and keep checking back on the new arrivals tab: https://thewodlife.com/collections/new-arrivals