To be fair, she wouldn't be the first PM in recent history to call a vote they were sure they'd win and live to regret it.

The real danger for her is presumably that MPs don't give her the mandate to hold the election at all, which would potentially mean we get yet another new and unelected PM.

She wasn't pro-brexit, it's difficult to say what her motives are. It does seem the enormity of brexit is becoming more apparent as time goes on, perhaps she would like a tight result to keep a lid on the right of her party.