Ever go to a thrift store and find an amazing art that you like off the bat. Then, you find some pieces that you feel need Improvement. You brainstorm how to improve on the art or in some cases, you just want the canvas. In these rare cases, where you purchase the art just to reuse the canvas, you can repaint over it and create new art.
Another Trend that Millennials are doing is upcycling the art. They will take an old Seascape or landscape and paint animals on it. In some cases, they will paint dinosaurs on it and make it a unique piece of art. Personalized to their Taste and to their decor.
Or they will take an old canvas and cover it with a fabric. For example a flag or Souvenir cloth from Italy. That's what I did to my vintage canvases.
Another way to update old art is to take an old poster print and use large scrapbook lettering and glue it to the poster after creating a message on it. I created a poster message that read dream big.
In summary, you can create all types of art with vintage art. Or is that is personal to you and creative in messaging. Are that is unique and one-of-a-kind instead of a dated piece of art. Art is what you make of it.