A pretty basic problem, but worth our time. If Management is always creating new Fields and brainstorming new ways to use them, you will need to know how to "see" these new fields in existing reports.
This is as easy as selecting Database | Verify Database.
Crystal will then poll the Database for columns and indexes (among other things). After the "Database is up to Date" message appears, you should be able to see any new fields or new tables that have been added to the Database.
You will also notice that there is a "Verify on Every Print" option. There is no harm in enabling this, but this is usually considered overkill as even the most zealous Management can only add so many new fields.
ProTip: Certain versions of Crystal will "detect" that something has changed in the Database (i.e. a new field), and will prompt you on opening if you'd like to "Fix up the Report". Selecting Yes to this dialog is equivalent to Verifying the Database.