Actually, the bits of dialogue with Saavik's Romulan heritage aren't actually put back into the longer TV version of Wrath of Khan. They did appear in some extremely low-quality footage shown at various Star Trek conventions over the years, though.

For my money, by far the most intriguing deleted subplot in that movie involves the lost scenes where it's revealed that Khan has an infant son of his own, whom he quite willingly blows up along with the Genesis Device in his last attempt at revenge on Kirk.