Outlook will continue to use your previous data file if you attempt an
upgrade installation.
In general, upgrade installations of office are a bad idea. While they are
alleged to work, I've never seen Outlook survive one until you create a new
profile. If you create a new profile, Outlook will then create a new data
file, and you will have to reset it to keep using your old one.
It's much better to back up your data thoroughly and do a clean installation
of Office.