I know it sounds vain, but really reincarnation should NOT destroy any colouring or hair style I have applied

It should default to you remaining the same (since your race isnt changing) with only an option to change back to default styles/colours .



True reincarnation can randomize visuals, you're supposed to be in a new body, new race etc. WIth lesser you're in the same body just with different stats, feat choices, skill allocations.