>If all my memories and everything will be erased before reincarnation
memories are just a perspective of an event, if the event can be reconstituted then one's experience can be conjured, given certain preconditions
>what difference does it make in compassion to void/non-existence?
assuming you meant 'in comparison' and to answer, you are more than your experiences.
>If after my death I won't get access to my previous incarnations why I'll be stupid enough to "try again"?
the purpose of all and any life is to individuate to a significant degree of oneself. you can get access to previous incarnations, but compared to the process of becoming they -- especially at the beginning -- are basically window dressing. First things first, you know?