By default, Auto Refresh runs at the interval you set until you stop it. There is no built-in cap on the number of reloads — unless one of two specific options is active and quietly cuts the cycle short. This guide shows the exact settings to verify so the timer runs uninterrupted.
In the Advance Options panel, the "Stop after" toggle does exactly what its name suggests: once the counter reaches the configured number, Auto Refresh stops. To refresh indefinitely, leave this option unchecked.

If you are using the Detect Keyword tool, there is a second stop condition that is easy to miss: by default, the cycle ends as soon as the keyword is found. To keep refreshing past the first detection, enable "Continue refreshing on keyword found/not found" in the Detect Keyword tab.
With both options set this way, Auto Refresh runs at the interval you chose for as long as the tab is open and the extension is in the Running state at the top of the popup.