How do you guys re-activate churned users?

I really want an answer to that!

Shipping new features!

Something that can help is- Delivering value beyond the core product: Adding extra value (such as bonus content, discounts, or other special offers) to the product can make it more attractive to users who are looking for additional benefits beyond what is provided in the core product.

I think reactivating churned users is really difficult - primarily because they've churned! Instead I'd say focus on those who are dormant - i.e., have some level of activity and are still subscribed to your platform - and bring them back up to a solid engagement level, however that is defined for your platform. As for churned users, depending on the reason they churned if the situation has changed you could always go back to them and see if they're open to a conversation. That said, anything you can do to identify churn indicators so that you can pre-empt upcoming churn - that's probably where time will be best spent.

Everyone finding the answer to this question

such a great question. waiting for the replies!

In addition to my last comment, just let them leave. Your product just might not be for them and that's okay. Understand what your product does and who it is for. That way when you see people leave you can say either "oh that makes sense they wouldn't need this" or "I thought they would use this. I need to figure out why they don't".

Ask them why they stopped using your product and re-evaluate what your product does for them. If users are leaving then that means there's nothing your product does to make them stay.

Personal follow up to gain feedback works when small enough scale - it's also a really good learning opportunity even if the user doesn't want to come back