I’m not sure about a respray (As I have no experience of this) but the other 2 options as far as I see it are:
1.Stove enamel (ala Argos racing cycles)
2.Powdercoat (ala local powder coaters)
1. Stove enamelling leaves an ultra hard coating which looks very nice but is prone to stone chipping IME – it’s also more expensive – roughly £110
2. Powdercoating is less prone to stone chipping, is a thinner coat so seems to scratch a bit more easily and is cheaper – around £30. You may find your local powder coaters have a limited colour palette. I found a powdercoaters near Southampton that did a very good job of masking/thread tapping etc.
Some places (Argos) also do a harder 2 pack coating in limited colours, but again I have no experience of this