use CSV to import and update whitout replacing empty fields

I need to use CSV file to import and update data in a regular basis.
The problem is that when CSV file have some fields without data, it delete the data from field on SuiteCRM.
How can I manage import wizzard to “ignore” empty fields?

When importing if you would not like a field to import any data. Set (on the field mapping page) the field to ‘Do not map this field’