Not matter if your website has been published already or it's just a draft, you can preview it from your Dashboard.
Do you have a website that hasn't been published yet and you want to see what it'd look like to your visitors?
Hover over the thumbnail of the website in question and click on the ellipsis (…) button. Then select Site preview to see it.
And if you’ve published your website, the menu item will simply be called Site preview.
Alternatively, you can also preview your website – published or not – straight in the builder itself when you're working on your website.
Simply click Preview and your website will reload in the same window.