The 25-year-old, who joined the Cobblers from Shrewsbury Town in June 2011, made 35 appearances last season, scoring once.
Northampton boss Aidy Boothroyd said: "This is a good opportunity for Jake.
"It will give him the chance to play regular football and he hasn't had that opportunity here.
"It is in the best interests of all parties that he plays regularly and we wish him well."
Luton are currently second in the Blue Square Bet Premier division, having won five of their opening seven matches.