Can I say "in my life" instead of "all in my life"?
Yes, you can switch the two without really affecting meaning. You can use "in all my life" or "in my life" to emphasize that you have never previously experienced something to such an amount before. While the "all" can be seen as putting even more emphasis to the sentence, it is not a big difference between the two of them. Ex: I have never been so scared in all my life. = I have never heard such lies in all my life. Ex: I have never been so scared in my life. = I have never seen such lies in my life.