When every a data load happend and for the next refresh of your .rpd, the IB query which gives the value to the variable will fire and pulls the new data and that data will be assigned to the variable.
Cache may effect this.
There will be an option in Initialization block refresh time, there you can set the time. ex: if we set for every 8 hrs then the initialization block will refresh and the values in dynamic variables will get refreshed.
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