The 19-year-old, who has been standing in for the injured Chris Dunn, is due to return to parent club Tottenham Hotspur on 5 September.
Jansson told BBC Radio Northampton: "As long as I'm playing, I'm happy to stay. But Chris is coming back to make it tougher for me.
"I hope I can play [in the Carling Cup third round], it'd be a great game."
The Sweden Under-21 international helped Northampton secure their spot in the next round as they knocked out Reading 4-2 on penalties following a 3-3 draw at the Madejski Stadium. Jansson saved Simon Church's opening spot kick while Jake Taylor blasted wide before Abdul Osman put the Cobblers into round three.
"[Goalkeeping coach] Tim Flowers asked me what my strategy was," said Jansson.
"I try to read the shooter. Simon Church looked at one corner first, so I went a bit early and got my hand to it.
"It was absolutely the highlight of my career so far. It was a fantastic game.
"We played so well, came back three times and won on a penalty shoot-out. You can't ask for anything more."
Jansson was on loan at Exeter last season, where his one-month deal was extended for a further two months.
Source: BBC Sport
Source: BBC Sport