text: Killie thumped Falkirk 4-0 to overturn a 1-0 first-leg deficit in the Premiership play-off final second leg at Rugby Park.
  But after only a third win in 14 games since he took charge in February, Clark said changes are needed by next season.
  "It is a celebration but tinged with a warning," he said.
  Media playback is not supported on this device
  "This club has been loitering in this position for four or five years before I got here. This warning needs to be heeded. We need to change the mentality.
  "The boys have bought into my methods and we haven't got what we deserved in some games.  But the position we are in tells me there needs to be a freshness to the group, and that is what we will do."
  Clark, who ran down the touchline in celebration after the third and fourth goals, grabbing a scarf from a fan on the first occasion, endured an emotional afternoon in the home dugout.
  "When the goals were going in, it was like what we did when we stayed up with Birmingham City [in 2014] and I never thought that would be repeated," he told BBC Scotland.
  "I knew what was at stake if we didn't get the result.
  "We couldn't have dreamed of a better start and that settled us a bit, but you know it is never over with Falkirk."
  Kilmarnock striker Kris Boyd, who scored the final goal, admitted a sense of relief at having come through the ordeal of a play-off decider.
  "It is a great occasion at the moment, but it is one you don't want to be involved with, and hopefully never again," he said.
  "It has been a tough season, but we have shown today we have got some good players and we are a team.  We think we can be a match for everybody in this division."
  His fellow forward Josh Magennis - who could be in the Northern Ireland squad heading to Euro 2016 - played an influential role on his return from injury, setting up two goals and causing Falkirk havoc.
  "To do it on the last day of the season was not what we wanted, but sometimes that's what it takes," he said.
  "Everything fell into place. We didn't let them breathe at all and we were all over them from the first whistle."
  Falkirk manager Peter Houston admitted his side failed to cope with the early intensity of the hosts, as their brave promotion bid came up short.
  "When you are two down after seven or so minutes, the occasion certainly got to us," he told BBC Scotland.
  "There are a lot of players in tears in there feeling like they have let the fans down.  But they have been magnificent all season and it is not a day to criticise the players.
  "We were involved in a cup final at the end of last season and a play-off at the end of this one.
  "We need to learn when we are in a position like that how to get it over the line.
  "We have to look at it in the close season. We need more quality and maybe more physicality in certain areas if you look at us compared to Kilmarnock.
  "We will re-group and see what kind of budget we have to bring players in."
target: Kilmarnock manager Lee Clark has warned the club needs to change personnel and mentality to avoid further brushes with relegation from the top flight.