Dion, who will be 42 in March, has endured daily hormone injections and painful tests to become pregnant, but refuses to give up. "I'm going to try until it works."
The mother of Rene-Charles, 9, underwent four unsuccessful IVF attempts last fall and suffered a miscarriage in August.
"Five's my lucky number," she added, "so this is the time it's got to work."
Dion also confirmed reports that she will be returning to Caesars Palace in a new $100-million deal for 70 music concerts a year for three years beginning March 15, 2011.
"Great songs, great lyrics. I think it's going to be very touching," said Dion.