The Magpies were cut from 9/2 to 3/1 for the drop after Reading boosted their own survival chances with a comeback 2-1 win at St James' Park on Saturday, while fellow strugglers Aston Villa and QPR all picked up points.
With just four points from their last eight games, Pardew's men currently sit just two points clear of the drop zone.
Saturday's defeat prompted Sky Bet to slash Pardew from 12/1 to 5/1 to be the next top-flight boss to depart, but subsequent backing saw his price cut to 1/2 on Sunday evening.
Sky Bet football trader Chris Spicer said: "We cut Pardew's price fairly significantly after the Reading defeat but money has come in ever since, forcing us to continually move his price.
"Suggestions that the club would only have to pay out 12 months of his eight-year contract seems to have fuelled interest, while their upcoming trip to Villa Park now looks an incredibly important fixture for both bosses."