Both Tractor Boys goals came in the first half, Jason Scotland and David Norris the men on the scoresheet, with Preston's consolation scored by Paul Coutts early in the second period.
Jewell said: "We're just glad the season's out of the way and we can start the job of putting a team together that's serious about challenging.
"There are no guarantees but the last few weeks have shown that we're quite a way from where we want to be.
"We got to a stage where the game should have been won but then didn't go on to kill them off. We didn't show a killer instinct and that's something we've got to have. It's one of the areas we need to improve on next season.
"Give Preston credit, they played well in the second half and pushed us back but from our point of view we have to do better. It's nice to get the victory and we were depleted. We were playing with a few square pegs in round holes."
Source: PA
Source: PA