Ask HN: Create a new product vs. adding a feature to an existing one?

I currently have a product that is selling decently. I want to add a new feature that will be very helpful to customers, however I could also spin it as a standalone product as it will potentially bring me more revenue (as the product is a one time license thing)

When should I do the former vs the latter? Any heuristics?

How do I balance improving the existing product vs launching new ones? Any thoughts are appreciated :)

Before someone mentions switch to SaaS, although it would be nice, the marketplace I am currently selling at does not allow SaaS.