Think of the total replacement value of the building.
The total replacement cost of your business contents. If you turned the building upside down and shook it, everything that falls out is what you'll want to include in this total.
The total replacement cost of things stored at your location that belong to your clients. Give the maximum value of property you would have at any given time.
The total replacement value of any improvements or changes you made to your leased property. Think of any enhancements, permanent fixtures, or equipment you installed in order to do business there.