The striker is currently on a season-long loan at Home Park and scored the only goal in Saturday's victory at Championship leaders Wolves.
He has also been out on loan at Stoke and Preston North End during his career, and has not made a Premier League appearance for almost two years.
Gallagher was hoping the appointment of Sam Allardyce as Blackburn boss back in December would boost his long-term prospects at Ewood Park.
However, after a brief meeting with Allardyce, the 24-year-old concedes he will be on the look-out for a new club in the summer.
"I've not really spoken directly to Sam about my future," said Gallagher.
"I went back to Blackburn for some treatment when I had a bad knee and shook his hand. The next thing I knew I was watching Sky and it said they were willing to listen to offers for me.
"To me that is pretty clear. It has been a long time coming that the club will say they are prepared to let me go and I will look for something new in the summer.
