Northampton lost a number of senior players following their successes in 2024, including Courtney Lawes, Lewis Ludlam and Alex Waller.
And Coles – who described last season as being like “a bit of a fever dream almost” – believes it is now time for others to step up to the mark.
“We came in on Sunday (after the Leicester game), really holding the mirror up to ourselves and asking, as a group, have we been in the right place enough over the season,” he said.
“It’s been well spoken about that we lost some of that experience within the playing squad and we just need to ask ‘are we going to take this upon ourselves and drive this team forward?’
“There is so much potential here and we’ve shown, in (some) games throughout the season, what our top level is. At the moment we’re not quite doing it enough.”
Northampton will warm up for the Clermont tie when they continue their league campaign with a trip north to take on Sale Sharks on Friday evening.
Asked whether it might be easier to be away from home for the first game following the defeat by Tigers, Coles replied: “I’d rather play at home again and try to pay back all our loyal supporters and give them a performance to be proud of.
“Sale are a very strong team, very well organised, we’re aware of their threats but the main thing for us is getting ourselves back on track.”
Alex Coles was speaking to BBC Radio Northampton sports editor Graham McKechnie.