Brendan Rodgers had outlined his team’s ambition to claim a top-four finish and Champions League football come the end of the season after victory over Tottenham but the loss ended the Red’s three-match winning streak and leaves them nine points adrift.
Liverpool are 8/11 to finish fifth or sixth this season with BetVictor
"It was a big disappointment against Southampton but Europe's not gone yet," he told reporters. "We've still got eight games to play and that's a lot of points to play for.
"We've still got to play some of the teams above us so we have to keep going. We have to pick ourselves up from this and ensure we respond positively against Aston Villa after the international break."
Henderson has endured a frustrating few weeks recently with his first-team exposure limited, but an injury to fellow midfielder Joe Allen has afforded an opportunity to force himself into manager Rodgers' plans for the run-in.
"I've just got to keep working hard," Henderson told the Liverpool Echo. "Before Saturday the team had been playing brilliantly so I can't complain.
"You can't really change a winning team so I've understood why I've not played. I just have to make sure that when the manager needs me I'm ready to take my chance."