I'm just going to list random ideas to revitalize those Keds.
Different laces -- ribbon or decorated laces or a measuring tape cut to be thin enough
Add buttons -- sew buttons all over it or on one side of the tongue and elastic hoops on the other side
Stencil images all over them in fabric paint or acrylic and fabric medium
Sew fabric shapes on them like stars or hearts
Hope one of those inspires you!