Tony Cousins came off the bench to earn Rovers a point with a late equaliser.
Substitute Cousins, back after injury, struck on 88 minutes to touch home a Billy Woods cross.
The game exploded into life with two goals inside a minute mid-way through the first-half.
Shane Bradley forced the ball home from close range to put Harps in front.
But, straight from the restart, Rovers levelled when Pat Deans beat Gareth Downey with a 25 yard effort.
Kevin McHugh then restored Harps' lead on 51 minutes before Cousins spoiled the party.