Happytoys review for Firebear Import & Export Tool

I need help: everytime i import a .CSV from an URL, the products are added instead of only rewrtitten the information that is changed. I need to know how to solve this. I have 12K products and now i have to delete all products and add them again... hence, I can not change items (URL, extra Tags, variants) since i have to delete all items and import them again. please help me.