Plaster stained and faded color

[New2water]

Our pool is about 15+ years old and the plaster color is variously faded and stained in some places. I've attached photos of the spa where you can see the stains and faded patches as well as some chipped plaster.
Other than re-plastering, what can one do to restore the color/finish of these surfaces?

 

[ajw22]

The chipped plaster in the spa you can patch with

Pool Interior - E-Z Patch

e-zpatch.com

The rest is cosmetic and can only be fixed with a replaster.