Noam Emeran had the hosts ahead at Carrington Training Centre before second-half strikes from Wanya Marcal-Madivadua and Lewis Brunt saw Leicester seize the initiative after Willy Kambwala was shown a second yellow card for a foul on Tawanda Maswanhise. Following Brunt's missed penalty, a second Emeran goal late on rescued a point for 10-man United.
The young Foxes came out on top against the Red Devils last month, winning a dramatic Seagrave contest 3-2, but were looking to respond to a 2-0 defeat at West Ham United last time out.
And Coach Ben Petty opted to make five changes from that side, with Harvey Godsmark-Ford, Joe Wormleighton, Deniche Hill and Marcal-Madivadua among those to be included in the starting XI.
An early opening for the visiting Foxes saw Marcal-Madivadua drive forward, twisting inside before Marc Jurado got back to head his left-footed effort off the line. Bobby Amartey headed narrowly over from the resulting corner, but it was a positive start with intent.
Maswanhise soon made his first impact on the game, creating space for a shot that looked to be heading for the far corner until Radek Vítek made a diving save to deny him an eighth PL2 goal of the campaign.
Former Man Utd youngster Chris Popov headed over from a Wormleighton cross as Leicester continued to look the more likely of the two sides to score.
The home side also threatened, from Emeran's cross - which was met by Joe Hugill - but the United forward did not get a clean enough connection on the ball to send it on target.
Back at the other end, Maswanhise's free-kick tested Vítek again, forcing the 'keeper into a smart stop to parry away.
A set piece would also lead to the hosts' best opportunity of the half so far, with Kambwala flicking over from Charlie Wellens' corner. They would not be denied moments later. Emeran took aim from range, finding the bottom corner to break the deadlock eight minutes ahead of the break.
In the mood for more, the winger went for goal again, this time from a tight angle, and found Brad Young in the way.
City held their one-man advantage from early in the second half and looked to make that count immediately as Vítek produced a save from Marcal-Madivadua and was also called into action by Brandon Cover, whose fierce strike required saving.
The pressure told 11 minutes into the half. Marcal-Madivadua found the net at the second attempt to equalise, after his initial effort was blocked inside the six-yard box.
It did not take long for Leicester to go ahead, with captain Brunt curling a superb free-kick around the wall and into the corner.
Chances continued to be created - Marcal-Madiavdua's deflected shot wrong-footed the 'keeper but he was able to readjust his body position to make the save, before Foxes substitute, Kian Pennant, wriggled his way into the box but again Vítek stood up to prevent a third.
City were then handed a golden opportunity to increase the advantage from the spot following substitute Sam Murray's push on Wormleighton in the area, but Brunt's penalty was saved by Vítek, who also kept out the rebound from Amani Richards.
United were far from out of the game and Murray, looking to make amends for his foul, struck over the crossbar from distance. The hosts did draw level courtesy of Emeran's second of the game, sending a free-kick past the diving Young on 84 minutes.
Spaces opened up in a frantic final few minutes. Maswanhise opted to shoot from the left, rather than play in Kian Pennant or Richards, but saw his shot flash past the far post., while Godsmark-Ford had to make a crucial intervention to block Dan Gore's effort from earning United a late winner of their own.
Major moment – The missed penalty
Leicester skipper Lewis Brunt had handed his side the lead with a fantastic free-kick, but then saw his spot-kick saved, which allowed the home side to grab a late equaliser.
Who impressed? – Wanya Marcal-Madivadua
The young Portuguese winger was full of running throughout, getting his reward with a goal early in the second half.
Where do we stand? – 14th in PL2
Moving on to 16 points, Leicester's Under-21s will finish bottom of the Premier League 2 Division 1 table and contest 2023/24 in Division 2.
Coming up – Everton (A)
The final fixture of the league campaign sees the young Foxes visit Finch Farm on Monday afternoon for a meeting with Everton Under-21s (2pm BST kick-off).
The details...
City: Young; Wormleighton, Brunt (c), Godsmark-Ford, Hill (Ali 59'); Trialist, Cover, B. Amartey (K. Pennant 59'); Marcal-Madivadua, Maswanhise, Popov (Richards 59').
Subs not used: Doherty, Grist.
Goals: Marcal-Madivadua 56', Brunt 64'.