I have implemented exporting dashboards data into excel in easy way - thought of sharing here .
Step 1 :
Create a view (Dashboard data) with data you want to display in dashboard.
duplicate view (Dashboard data) as crosstab and name it as "ExporttoExcel"
make sure you convert all the measures into Discrete and arrange them in row shell
add ExporttoExcel view into dashboard and make sure all the filters are applied to this View.
resize the view to 1 which will not show anydata it will looks like a small Icon.
Step 6. while your exporting to server you have to select the view ExporttoExcel - magic works here.
Step 7. you can download into csv based on your filter selection.
hope this helps you . feel free to reach me if you have any question.
attaching screenshot and workbook for references.