United bowed out of the Champions League on Wednesday night with a 3-1 defeat which sent Bayern Munich through to the semi-finals 4-2 on aggregate.
United's season is now effectively over. There is little hope they will be able to bridge the seven-point gap that separates them from fourth place given that just five matches remain.
But the players who have let the club down in what has been a very disappointing campaign must not allow their season simply to fizzle out, according to Fletcher.
David Moyes will embark upon a multi-million pound re-building scheme over the summer. The Scot has already held discussions with targets who he says are keen to come to Old Trafford despite United's failure to qualify for Europe's top club competition.
Current players will have to be moved out to accommodate the new arrivals so Fletcher knows places are up for grabs.
"The boys have got to play well to stay in the manager's thoughts for next season," the United midfielder said.
"There is talk of a lot of changes so if you get an opportunity to play you have to go out there and perform and to show the manager that you want to be at United, that you are capable of being at United and you are good enough.
"A lot of people will say there isn't a lot to play for now, but there is - you are playing for personal pride and to be in the squad for next season."
As the United squad filed out of the Allianz Arena late on Wednesday, the disappointment of exiting the Champions League was clear.
The 3-1 score line looks comprehensive, but Patrice Evra's opener gave the Manchester United players and fans hope that this would be another night like 1999.
But there was another reason for the disappointment - the knowledge that there would not be another night like for at least one season.
Unless United win all their games and their rivals all suffer dramatic collapses, the Red Devils will not be in the Champions League draw next season for the first time since 1995.
Fletcher has seen United reach three Champions League finals during his 14-year spell at the club, so the idea of not being among Europe's elite does not sit well with the proud midfielder.
"Watching the Champions League (on television) next year will be difficult to take," the Scot said.
"We are used to playing in it all my career. This will be the first time we are not there.
"Hopefully the biggest thing that can do is give you more determination to get back in it.
"It is the pinnacle of club football and Manchester United need to be in this competition.
"As a player it's the best feeling to play in the stadiums like the Allianz Arena against top quality sides. We have had success in it in the past and I am sure we will in the future."
The need for defensive reinforcements was clear on Wednesday as Bayern equalised Patrice Evra's opener just 22 seconds after the restart.
Moyes needs to sign at least one centre-half, along with possibly two full-backs. The midfield needs a ball winner and a creative playmaker while the lack of width also needs to be addressed.
Those deficiencies are some of the reasons why United are some 17 points behind Barclays Premier League leaders Liverpool.
As a man who is used to success at every level, Fletcher wants United to bounce back in style next year - by winning the Premier League.
"Next year we won't just think about getting in to the Champions League, we will think about winning the league and getting into Europe that way," the 30-year-old said.
"The gap is not as big as people think."We have some fantastic players. There will be some signings too and hopefully they can take us to where we want to be."
The idea of trips to far-flung places in eastern Europe may not appeal to many, but Fletcher thinks United should not turn their noses up at the idea of playing Europa League football.
"We should embrace it," he said.
"Let's go and win it."