Click on the "Download" menu bar of Kuwo Music Box. The left column has two columns: "Downloading" and "Downloading Recently". Find the song you want to download again, click Play, right-click the name of the song in the playlist on the right, click "Delete Local File" in the pop-up menu bar, delete the original song on the computer, and then clear the download record of the song to download again.
Deleting the download record will not delete the local song file at the same time.