The 22-year-old American made 10 appearances for the Cobblers from the substitutes' bench last season.
"I have seen an improvement in Seb as the season has gone on and he will be all the better for the experience of last season," said boss Ian Sampson.
"He can play as a striker or as a centre-half and that versatility is important," Sampson added.
"He has a first-class attitude, he is one of the hardest working players you will find and he is desperate to make the most of the chance we have offered him."
"We have invested some time in him and we will continue to do that and I hope he will continue to progress," Sampson continued.
"Next season he will be challenged with kicking on again and to try and challenge for a starting place."
Northampton Town have released strikers Gary Mulligan, Joe Benjamin and Stephen O'Flynn so far, while Steve Guinan has been transfer-listed.
Meanwhile top-scorer Adebayo Akinfenwa has also left Sixfields, having rejected the club's contract offer.
"We are still looking at recruiting in various positions including up front and my work in that area is ongoing," added Sampson.
Source: BBC Sport
Source: BBC Sport