Clean first. It would be a labor of love to un- sew the parts the mice borrowed for their mouse house, they have good taste!
Find similar fabrics and re- piece those few spots. It can be done if you feel the rest of the quilt is worth it. If the fabric seems sturdy and not dry rotted it would be one of those accomplishments that would certainly make me feel good. I really like the pin wheel in blue and white.
Good luck and please update as you go! Thanks for wanting to save a simple sweet quilt.
peace