Yes, you do have to keep creating new content. The good news is that you can also repurpose a piece of content in many different ways. You could, for instance, take a few related blog posts and repackage them as a free eBook for your mailing list subscribers. Or, you could take the charts/graphs/data points from an eBook and design an infographic. Essentially, you could turn any form of content into a completely different form of content, with minimal effort and without worrying about penalties from Google. Nothing gets wasted!