To jazz up something means to make something more exciting or interesting, usually by embellishing it in some way.

1. The food looked a little dry, so I jazzed it up by adding a spicy sauce to it. 
2. I jazzed up the plain wall by hanging some paintings up.

1. Your article is factually sound but needs to be made more interesting to readers. Can't you jazz it up a bit?
2. The design of the product is too bland to appeal to a young audience. We need to jazz it up, perhaps by adding some bright colours.