Be able to upload reversing journals (which reverse in the following month)

I post a lengthy month end journal each month which I reverse in the following month. I would like to do this as a csv file upload each month. When using the Journal Importer, as part of Step 3 'Define the mapping between target and data source' if I click on 'Options' I can choose to 'Reverse postings'. However, this reverses the postings in the same month. Please could there be an option to reverse all the entries in the following month.