in pulumi, do you pay anything extra if you run

pulumi up

or

pulumi preview

many times?

No, for the core product, I believe you are only charged for the number of resource hours (so resources in your program * how many hours they are active in the month) you are using. For other products like Pulumi deployments, there are factors like minutes used/available etc. that you should consider.

Assuming you are using the Pulumi cloud service, and not on the free tier then you are charged for the amount of resources you have deployed, so the amount of times you deploy, destroy, update them does not incur a cost. If you are using the open source product with your own state backend, or local state, then there is no cost at all