I think she went to study abroad to change herself
I think she went to study abroad to discover herself
質問者様のお求めの英語は「I think she went to study abroad to change herself」になります。直訳です。
しかし、自分を変えると言うよりは、「自分を探す」の方がキレがあるかもしれないので、同時に「I think she went to study abroad to discover herself」を提案しました。