The Cottagers reached the 40-point mark some weeks ago, but are without a win since the beginning of April, and are still not mathematically safe from the dreaded drop.
Jol knows this, and believes that his players have taken their foot off the gas a little too early.
"Maybe we reached the 40 point mark too soon," he told Sky Sports following the 4-2 home defeat by Reading.
"In hindsight, if we hadn't, then maybe we would be playing with a little more determination than we are at the moment.
"Today's performance was a bit embarrassing, especially in the first half."
With only two games left in the Premier League season, Jol's side sit five points clear of the relegation places, but with difficult fixtures to come, he may have to rely on other sides slipping up.
"We have two tough games to come," he added.
"But sides down at the bottom have to play each other, so we will see what happens."