The Cottagers struggled in the opening period of Saturday's Premier League game against the Hornets before hitting back to snatch a point in a 1-1 draw.
Slavisa Jokanovic's side return to action on Tuesday evening when they travel across London to face the Lions at The Den.
And Ivory Coast international Seri has urged his team-mates to pick up where they left off.
"The boss saw it early, which was good for us," Seri said of the poor first-half display against Watford, according to Fulham's official website.
"The changes happened and you could see we were better in the second half.
"We have to look at the second half and try and take that into the next game.
"That was a positive for us and we have to continue like this."
Fulham have made an indifferent start to their top-flight campaign following promotion via the play-offs in May.
The weekend result leaves them with five points from six fixtures and just one win.
Top scorer Aleksandar Mitrovic's fifth goal of the season earned the draw against Watford after Andre Gray opened the scoring at Craven Cottage inside two minutes.
"Every game we play, we play to win. But if we can't win, then we have to make sure we don't lose," added Seri, a summer signing from Nice.
"We took one point against a team who are very difficult to play against, and it's a good result for us."