I have a spreadsheet that I update monthly to track sales by company. I
originally got the format from a former co-worker and couldn't figure out if
he maintained it manually or if there was a more automated way of updating it
each month. It's basically set up like this:

Column A = Company Name
Column B = September Revenue
Column C = October Revenue
Column D = November Revenue
etc.

There are hundreds of rows of individual companies and each month I have to
add a new column for the month's revenues. What I've been doing is pasting
in the newest month's list of revenue by company (for instance, November) to
the end of the data already in the spreadsheet, moving the list of new
revenue over to the November column, and then sorting everything by company
name (col. A). Many of the companies are existing clients that buy each
month so I end up with:
Company Sep Oct Nov
Row 1 = Jones Harbor LLC $200 $200
Row 2 = Jones Harbor LLC $200
Row 3 = English Brakes Inc. $175 $900
Row 4 = English Brakes Inc. $350
Row 5 = Greene & Sons $550
etc.

I have to manually move the revenue in the Nov. column up one row to the row
containing the continuous data. (i.e., I'd move the $200 in cell D2 up to D1
and D4 up to D3.) I'd prefer not doing it manually as it takes forever and
leaves room for error. Is this even possible?