Freddie Sears's fourth goal in five games was enough to give Colchester victory over the Lilywhites, who had defender Bailey Wright sent off near the end.
Westley offered no excuses as he said: "You get what you deserve in life and in football and you can't look for excuses.
"We have to get ourselves out of this rut of not winning games and we have to look at ourselves as individuals.
"There are little things that we have to look - we need to get the technical things right. Had we done the simple things better, then we'd be standing here with a better result.
"The work ethic over the 90 minutes was solid and the difference between what we're doing and winning is very slight at the moment.
"But we need to make sure that we get over the line better.
"I can think of at least three moments when we came very close to scoring, but we're conceding soft goals and at vital moments, we're making errors.
"We can't point to the officials for the result - we have to take responsibility."
Preston's Lee Holmes hit the crossbar with a curling shot with 18 minutes to go, but the visitors' hopes were ended when Wright was sent off following an off-the-ball altercation with Ibehre with eight minutes remaining as Colchester secured a crucial win.