P.S. I also agree with Lola, that the construction would have to read "Had she been alive today, she would have wanted you to become a doctor."

I believe that both constructions could be permissible, but that the correct choice would depend on the circumstance of the person being addressed. I think the first example would be used if I were speaking to you about, for example, our mutual deceased grandmother : "[she] would have wanted you to become a doctor..." but you chose to become a teacher, instead (i.e. you already made an alternate choice). The second example, in my opinion, would be used if you were still in the process of making a decision and we were speaking of our same aforementioned mutual grandmother: "I know you haven't yet decided, but I just thought you should know that [our deceased grandmother/she] would want you to become a doctor, if she were alive today".