Generally, I tend to do this in vector images as they lend themselves beautifully to be reworked.
This image was first created in 2010. I remember I was so proud of it as it was one of my first images in vectors of it's type (transparent layering, working shapes etc with the pen tool).
I recently found it again and followed the urge to 'tinker' with it once more and I have to say, it looks much more like the original idea in my head than what the older version did.
I'm pretty happy with it now (again) but we'll see in another 4 years if it doesn't get altered again. :p
Larger size version of the new image can be seen in my vector gallery: http://mveronicasilva.weebly.com/vector.html