If I use the same column names in my underlying database tables, is it possible to use them in an existing report to refresh data for new quarter without wiping out my existing reports? The reports took a long time to set up so I hope I can do this. If it is, can you please point me in the right direction?

If you mean "can I base two tablixes on the same dataset but apply different filters to each one", then yes. You just right-click the tablix, select Filters, and change the filter. Since the two tablixes are different, they don't have to have the same filters applied.