Memorise function for invoices

In Sage 50 I set up an invoice template for a very large invoice of 58 lines (and getting bigger) that I need to post monthly. All I needed to do was pull up the memorised invoice, change the dates and a couple of minor things, then post it. It would be useful to have this again as it can take hours to post it otherwise, a I found out this morning. I did try doing a csv upload on test sage, but it posted it as separate lines, which is no good at all. Is there a way to upload a large invoice with multiple splits by csv, or memorise as before?