Hello, Jude. Epoxy resin is probably the best finish for you. Re-plastering will only crack and leak again in a year or so. Could you just tell me, please, what is the finish on the walls of your pool at the moment? Is it bare plaster, paint, tiles, something else? Once I know that I will post a complete abbreviated specification of work for you to consider. Also, are you able to do work such as painting yourself? If so, using epoxy resin will produce a superior finish that the material manufacturers will guarantee for ten years but will in fact last at least twenty for a cost to you of only a few hundred dollars.