The League Two outfit defeated Brighton, Reading and Liverpool to reach the fourth round but they bowed out of the competition on Tuesday night, beaten 3-1 by Ipswich Town at Portman Road.
"A lot of our young lads have more than matched themselves against so-called better opposition," Holt said.
"They need to take massive positives from this and take it forward into the league now.
"Hopefully if that happens I'm sure we'll be good enough to start moving up the table," he added.
Younger players like Michael Jacobs, Liam Davis and Abdul Osman all impressed during the Cup run - but Northampton's immediate priority is pulling away from the League Two relegation zone.
"It [the Carling Cup] has gone now. We had the highs of beating Brighton, Reading and Liverpool and they were three fantastic results.
"We've lived the dream for a short period of time but now we need to get it out of our minds as soon as possible.
"The most important thing is moving up the league."
Source: BBC Sport
Source: BBC Sport