The Millers, who had scored injury-time winners in their last three games, this time struck in the 89th minute to earn a draw in a game they thought they had thrown away.
Steve Evans' men had enjoyed a dream start as they raced into an 11-minute two-goal lead. First a superb piece of skill from Frecklington created some space and the midfielder finished high into the net from an acute angle. Then a wicked delivery from Ben Pringle flicked off the head of unfortunate Preston defender Tom Clarke and into the corner.
But, despite their deficit, the hosts were the better side and pulled one back eight minutes before the break when Paul Gallagher's clever lay-off found Craig Davies and the on-loan striker fired low into the bottom corner.
And within 15 minutes of the restart North End were deservedly level when Gallagher turned on the edge of the box and curled a low effort past Adam Collin.
Preston thought the comeback was complete five minutes later when Joe Garner headed home Chris Humphrey's cross.
But Frecklington had the final say, firing in from 18 yards to earn a point to stretch the Millers' unbeaten run to eight games.