You could save the first report, with comments, to a 'master workbook'
which you would use to add comments. When you run new reports, save
them to a different workbook and use VLOOKUP (either manually or by
code) to re-insert the comments back into the new report. Then you
could do a couple of things at this point:

1) Sort the data so the new entries (the ones that aren't in the
master workbook) are grouped together and then paste them into the
master workbook, where you would add new comments;
2) Use a macro to compare both worksheets and copy new rows from the
new report into the old report, where (again) you would manually add
new comments;

ps- what format are you using to import the data?

HTH,
JP