Ross Wallace - who was signed by Keane during his tenure at Sunderland - fired Alan Irvine's side into a deserved early lead before Callum Davidson was dismissed for handling a goalbound effort.
Jon Walters saw his penalty saved but managed to score the rebound but despite heavy pressure Ipswich were unable to find a winner after the break.
The Tractor Boys remain winless in the league this season to leave Keane under fire.
Keane made four changes as he recalled Gareth McAuley to the heart of his defence but it was the visitors who should have opened the scoring in just the third minute.
Billy Jones sent a hopeful ball forward and McAuley's defensive partner Pim Balkestein misjudged the bounce horribly to allow Jon Parkin a clear run on goal.
The striker charged into the area but could only rattle his shot against the legs of Ipswich goalkeeper Richard Wright.
It was a let-off for Ipswich but Preston did forge ahead in the 12th minute.
Liam Chilvers hit a magnificent crossfield pass from defence to pick out Wallace in space on the left flank. The former Sunderland man ran at Alex Bruce and after cutting inside, and then outside the new captain, sent a powerful shot across Wright and in off the far post.
Parkin had another chance to double the lead but failed to control the ball inside the area before the home side stole an equaliser on the cusp of half-time.
Jack Colback's cross was flapped at by goalkeeper Andrew Lonergan and Liam Trotter's shot was handed by Preston captain Davidson.
He had already been booked and was duly sent off by referee Paul Taylor.
Walters saw his penalty well saved by Lonergan but the forward was first to the rebound and slotted home at the second attempt.
Balkestein had a long-range shot which flew wide as the hosts started brightly in the second period before Tamas Priskin saw a close-range header brilliantly cleared off the line.
Chris Brown flashed a header wide at the other end as Preston mounted a rare attack but the home side were now dominating possession as they looked to make their extra man count.
Keane brought on Jon Stead, Alan Quinn and Connor Wickham in a
triple substitution as he searched for the winner and was almost rewarded when 16-year-old Wickham tested Lonergan from the edge of the area.
Wallace called Wright into action with a powerful effort from the edge of the area but neither side managed to find a winner.