The Panners edged past Tynecastle 2-1 at Saughton Enclosure, but fell behind to Ryan Mayer’s opener after 15 minutes.
However, the visitors drew themselves level on the half hour mark when on-loan Spartans winger Jonathan Grotlin’s well-executed lob was adjudged to have crossed the line.
Whatever Preston’s joint-management team of Paul Riley and Jack Lynch said at the half-time interval worked wonders as the Pennypit side notched the winner 42 seconds into the second half, Mikey McFarlane applying a cool finish.
Preston will now look to end the season on a high at Kings Park in Dalkeith this weekend (kick-off 2.30pm) but face an almighty task in trying to topple Kelty, who stormed to an 8-1 win over Leith Athletic in the other semi-final tie at New Central Park.
For Tynecastle, Friday’s defeat marked the end of head coach Stevie Vinter’s three years at the club. Vinter is relocating to London and will be replaced by Chris Scott.