The 23-year-old spent the 2019-20 season on-loan with the Millers, scoring twice in 27 league appearances.
Magpies boss Steve Bruce told the club website: "He had a wonderful loan spell last year.
"He's got to an age where I think he needs to play, and I hope he goes and has a great career."
Barlaser could feature for Paul Warne's men at Huddersfield on Saturday.
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