In general, you can't automatically "create" or "generate" stuff in excel without macros.
However, if it were me, I would create a simple PivotTable on a new sheet based on your source data (including blanks for future months), and create a PivotChart from it.
What's nice about a PivotTable is that changing the month (and therefore the chart) is as simple as clicking refresh and selecting a month in a drop-down filter menu. Other users could easily do it too.
If you want to keep past charts, you could copy that sheet and change the month in the drop-down. If you want the month in your chart title, I would use a formula to pick the date from the cell with the Pivot month filter and show it well formatted (eg: 2012-08-01 -> August 2012) on top of the chart (as you can't put formulas in chart titles) to automate that part.
Basically, whenever you would have added a new month's data, you would merely have to:
- copy sheet
- refresh the pivot
- change filter to the new month
I wouldn't recommend attempting to automate even these few steps through a macro. It's a lot of hassle: when would you fire the macro and how to prevent a bunch of empty or duplicate charts being created?
I find doing these few steps manually is probably the simplest and less error-prone way to go.