If you declare your variables, I assume your C-compiled program uses a routine to clear the variables upon initialisation.

If you reset your processor the fact that your program restarts would then effectively mean that your variables are initialised again, and hence lose the value they had before the reset.

If you want values to be retained between (warm/hot/cold) resets then you should use eeprom memory (or flash or some other non-volatile memory) as already suggested. RAM memory is not to be used for this.

regards
Patrick