Can I just add a part to the paper that was polished before to polish this part?
Of course. Before polishing the paper, modify and add a part, and only this part can be polished. Usually retouching means that the main body of the article has been fixed, and the reviser can look at where the words are not fluent and where there are technical errors and polish them. In the words of ordinary people, it is to find faults and deal with them. In fact, they are all minor problems, so they are ok.