The following is from the Huffington Post.
Fox News' Liz Trotta Doubles Down On Statements About Rape In The Military (VIDEO)What is the meaning of "double down on"?
(Not a Teacher)
A 'double down' in blackjack is doubling your initial bet. So, basically, it means the same thing as 'raising the stakes' here. She's putting her reputation or career on the line by standing by her statements on rape in the military.