Hi Rostam, If you hope that someone is "doing good", you may be misunderstood that you hope he or she is doing good deeds, helping others and performing altruistic acts. I presume that this is not what you meant. Instead, we wish someone well by saying that we hope they are "doing well". However, if you use "going well" with "as well", the sentence can be phonetically clumsy though it's not ungrammatical: "I hope you've been doing well as well." Someone who is not listening to you attentively may mistakenly think that you are using the expression "as well as" which means "in addition to". You can substitute "as well" with "too": "I hope you've been doing well too." In this way, you will avoid any ambiguity.

You can say "I hope you've been doing good, as well" in casual/informal/colloquial English. "I hope you're doing well" works fine and so does "I hope you've been doing well." You might want to avoid saying "I hope you've been doing well, as well" but you could and it would be grammatically correct. It wouldn't be that weird. To avoid saying that you can say "I also hope you've been doing well" or "I hope you've been doing well too."