And in the past few weeks, she has visited Hong Kong, London and Northern Ireland, where the show is filmed. Castle-Hughes moved to Los Angeles soon after marrying DJ Jonathan Morrison on Valentine's Day last year.
Morrison has since returned to New Zealand, but Castle-Hughes told the Herald on Sunday that she was staying in the US to chase her dreams.
She had just finished a busy pilot season when she returned to New Zealand last week to co-host four performances of live Kiwi variety show Happy Hour.
Game of Thrones received a record 19 Emmy nods this week, the highest number of nominations this television season.
Castle-Hughes' new manager could not be reached for comment.
Meanwhile, US entertainment bible Variety has heaped praise on New Zealand cult TV series The Almighty Johnsons, in which Castle-Hughes also appeared. Reviewer Brian Lowry said the series "is certainly a cut above".
"It will be easy to develop a pretty sizeable crush on The Almighty Johnsons," he wrote. The show is screening in America at 9pm on Fridays.