An easy way to improve content is simply by highlighting sentences within your document. Use your cursor to highlight the section of text you wish to rewrite and click the Ask Jasper button that pops up and then click "Improve Writing".
Rewriting will change out a few keywords, but the general gist of your sentence will remain.
Are you receiving the same text back when you highlight and rewrite? Go ahead and change what you are highlighting. Try highlighting a smaller section of the text. This will help to decrease the repeated outputs.
Do you like a sentence and want to keep it for later? Change it out and copy and paste it to another part of your article. Then command + Z to get back your original output.