Only took however long it took for Beth to murder Froopyland for Rick to regrow his arm. At this point however much of Rick is organic or cybernetic are irrelevant. It will always keep changing as time passes.
What does beg to question is this:
Question: you take a broom, you replace the handle, and then later you replace the brush. And you do that, over and over again. Is it still the same broom? Answer: no, of course it isn’t, but you can still sweep the floor.
You have replaced every piece of yourself, mechanical and organic, time and time again. There’s not a trace of the original you left.
- 12th Doctor, Doctor Who