Reduce the horizontal axis

Hi

I have a graph on a sheet which changes regularly. It is a sprint chart for 15 days most of the time. However, if there is a bank holiday within a sprint then this is reduced to 14 days. And more recently I want to run a 2 week sprint so I want the axis to reduce to 10 without having to create a new graph (as I just copy the sheet and all of its data/graph)

If I amend the axis using the edit function it reduces the text of the axis to 10, but the line remains at 15! How do I dynamically get the axis to change?