I don't think there is any such thing as "proof".
You can either 1) see something for yourself or 2) take somebody's word for it.
What we call "proof" is really just instructions on how to see something for yourself. In geometry class if you follow the steps of a proof of a theorem, and if you understand those steps then you see the truth of the theorem for yourself.
If you follow the steps of the proof but
don't understand the steps, then you are have to the teacher's word for the fact that it's true.
You say science can "prove" the electrical charge on an electron. How do you know that? You took your science teacher's word for it. On the other hand, you could also set up the Millikan apparatus (
http://en.wikipedia.org/wiki/Oil-drop_experiment) and and see it for yourself. But those are, in fact, the only two choices.
Likewise, a mystic can't prove that enlightenment is possible, but can only supply instructions on how to meditate so you can see for yourself.
So, if, as I believe, there is an afterlife, and reincarnation, then either we have to take somebody's word for it, or we have to see it for ourselves. There are various different ways to see it for ourselves: 1) Remembering that we have already seen it for ourselves, 2) Using some form of deep meditation to reach some mystical state of enlightenment where we can see it for ourselves, 3) Waiting until our time to leave this life and see it for ourselves while we are between lives, 4) Collecting and analyzing the testimony of others who claim to have seen it for themselves.
I think that if reincarnation is ever proven it will be by discovering some new method for allowing people to see for themselves the truth of it.
And never forget that there will always be those who take the attitude of one famous skeptic who said "This is the kind of thing I wouldn't believe in even if it were true." (
The Mind Field Robert Ornstein. pp85)