How do you ask an URLSession.dataTaskPublisher for a data refresh?

I started looking into Combine just a few days ago, but I can't seem to find an answer to this. I have an instance subscribing to a URLSession.dataTaskPublisher, but I can only request data once. The second time (via a "refresh" button) I try to ask the publisher to provide more data, the request is never repeated.
How could I force a publisher to retrieve more data and repeat the request?
How do you ask an URLSession.dataTaskPublisher for a data refresh?
 
 
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