Refreshing public shared dashboards

We created a few dashboards with static and dashboard parameters and shared the public link with our customers.
we want the public dashboard to refresh every 12 hours (or alternatively refresh when it’s opened)
We tried adding &refresh=1 to the public url, it refreshes the dashboard only after a while.

Yeah, I’d like to know how I could refresh a dashboard right after opening the page too. :frowning: