We never deliberately create new profiles to merge with existing ones.
You could edit the individual profiles manually to revise the erroneous content from the old gedcom.
Or you could upload your new Gedcom file to WikiTree. Then go into the WikiTree GEDCOMpare utility, use GEDCOMpare to match each record in your new Gedcom file to the existing profile for the person, then use GEDCOMpare to edit the individual profiles with data from the new Gedcom.
I can't see any ancestry for you in WikiTree, so I can't guess at what you are thinking of working on. However, I think that manual editing is likely to work out best for you. Before existing profiles with GEDCOMpare, it's advisable to have a good bit of manual editing experience under one's belt (otherwise it's too easy to make a mess).