Cleverly, 29, will face Braehmer for the WBA regular light-heavyweight belt in Germany on 1 October.
The Welshman's three career defeats have all come in his last six bouts.
"This is a must-win for me - I'm confident I can upset the champion," said Cleverly. "I believe this is my opportunity to turn things around."
Cleverly and Braehmer were due to meet in 2011 before an eye injury forced Braehmer to withdraw.
The German will be aiming for a seventh successful defence of his title, while Cleverly lost his WBO crown in 2013 when he was stopped by Sergey Kovalev.
Asked if this would be his last world title fight if he lost to Braehmer, Cleverly told BBC Radio Wales Sport: "Possibly so and probably so.
"I knew the world title opportunity would come back around.
"Sometimes you hit those plateaus - you peak and then have a bit of a flat period. But I think I've got through that and the best is yet to come."
The WBA super world light-heavyweight title - the body's top honour in this weight division - is held by Kovalev.
Cleverly's last fight was a points defeat by Andrej Fonfara in Chicago in October 2015, though he was encouraged by his performance.
"We [Cleverly and Braehmer] were meant to fight three times in the past but he never fancied the challenge when I was at the peak of my game and had a lot of hunger and fire," he added.
"Maybe he's taken the fight now thinking I've had a quiet couple of years and gone off the boil.
"Maybe he's thinking this is his opportunity to beat me but, as I showed in my last fight, the fire is coming back.
"I'm looking to become a two-time champion and I'm going to grab it with both hands.
"It's notoriously difficult for boxers in Germany against the home fighters, but I'm confident that I'm not just going to win, I'm going to win emphatically and take it out of everyone's hands."
Welsh former world champion Nathan Cleverly believes his world title fight against Juergen Braehmer can be a turning point in his career.