The stopper made a series of good saves to keep his side in the game after Tadanari Lee had put them in front from the spot.
But Federico Macheda levelled nine minutes from time before Lee missed the opportunity to score his second penalty of the night, leaving the squad frustrated not to have sealed the win.
However, Cropper insists the team will take positives into their crucial home game against Newcastle in two weeks' time.
"I think it is two points lost," he admitted to Saints Player
at full time.
"I think we played well at times, although we made some errors that we'll fix on the training pitch.
"Overall, I think it was a decent performance. We can take a lot out of that into the Newcastle game so we can hopefully get something out of that."
Cropper's personal showing was a highlight of the evening, with the American pulling a number of superb stops to keep Macheda out for the majority of the game.
And the former Ipswich man said he was relatively pleased with his evening, adding that he was simply glad to be back in action having recovered from a two-month injury lay-off.
"When you play against players like that, you're always going to be tested," he said as he assessed his performance.
"I think I played well but there are things I can work on, as always. I'll get down to work and hopefully by the end of the season or next season I will be pushing for the First Team.
"Last year I spent three months out with the same knee problem, so it's just good to be back playing again. This was one of the games I was aiming to get back for."
Saints will need three points from their final game in the First Group Stage if they are to finish in the top three and qualify for the Elite Group Stage.
And Cropper says he and his teammates are already focusing on that crucial home fixture against the Magpies at Eastleigh's Silverlake Stadium in a fortnight's time.
"Now we're just looking forward to the Newcastle game," he affirmed.
"We need three points – there's no question about it. It's down to us, and I'm confident in the boys."