If it is just a music portion it is easy. If you need music and voiceover... not so much. You can replace a section of your audio in YT Studio. In Studio, go into Edit, and there are tabs for Details, Analytics, Editor, Comments (the side bar). Go to Edit. You can use a music track from the YouTube library and it will cover the original track. You will also lose any talking, though. You can add multiple tracks and adjust the level of each but I do not know if you can upload a new audio track, if you need talking.