I think I would like to go back to that time just before I die.
I think I might like to return to that time in my life the moment before I leave this world.
この場合、次のような言い方ができますよ。
ーI think I would like to go back to that time just before I die.
「死ぬ間際に、あの時に戻りたいと思うだろう」
just before I die で「私が死ぬ間際に」
ーI think I might like to return to that time in my life the moment before I leave this world.
「この世を去る瞬間、人生のあの時に戻りたいと思うだろう」
the moment before I leave this world「私がこの世を去る瞬間」
ご参考まで！
I'm sure that when I'm drawing in my last breath, I would think that I want to go back those days.
ご質問ありがとうございます。
"I'm sure that when I'm drawing in my last breath,"＝「私が息を引き取るときにきっと～だろう、」
（「死ぬ間際」は "when I am about to die"とも訳せます。）
" I would think that I want to go back those days."＝「私はあの日々に戻りたいと思うだろう。」
ご参考までに。
カナダ 
アメリカ合衆国 
