Repair or replace?

My roofing material has shrunk. The seams are not pulling apart, but it is pulled away from chimneys and out of the terminating bar in areas around the edge of the roof.

When it was originally installed the brand was Kelly Whaleskin. I believe it is EDPM. It is a single ply black rubber.

Is it possible to reseal all seams, cut away & replace all protrusion flashings (2 chimneys, & 2 plumbing vents), & add new additional roofing material around the outer edges (to extend the roofing)?