To all THOSES Pokeman Fans
I need help

In 5th Grade I played The Pokemon game HeartGold for my first time and I beat the Champion but I didn't play through the whole game and beat them a second time.

SO

I'm thinking that I should restart and play it now that I'm old and make a better team and stuff like that BUT I DONT WANT TO FORGET THE POKEMON I HAVE😭(and before you ask I don't have a second DS so I can't transfer them ): 

WHAT DO I DO