Merging new data into an existing ZOHO Database

Merging new data into an existing ZOHO Database

We have a spreadsheet with some additional information on about 3000 records inside of ZOHO.   Only two of the fields will be changed and I don't want to change any other data inside of ZOHO on those records - just those tow fields.   In the past I just did a MassUpdate, but that is limited to 100 records at a time - time consuming and tedious.  Is there a way to do this with an upload without affecting any of the other fields?