Although there are many discussion threads on this topic I haven't found it as an "idea". So here we go:
Dashboards are great for drilling down into data but not great at all for getting back. Using the "undo" button is not always practical. It would be great to have a "clear all filters" button for dashboards.
An easy version of this could be a button to set all dimensions in a dashboard to "all". A more advanced version would be to set to a pre-defined set of filter values. This would allow for a quick way of getting back to the initial state.
PS: if this is already captured in another idea please let me know and I will cast my vote!