Go to the Settings menu, Document Properties, Triggers tab, OnOpen and add a new action type External, Run Macro. Click on the "Edit Module..." button and use the following piece of code:
Sub ReloadOnOpen ActiveDocument.Reload End Sub
Click OK and set the name of the macro to ReloadOnOpen.
If you are using QlikView 11 it does have an action to Reload, use it instead of the macro code above. Note that this code might not work in a server environment.
Hope that helps.