mtt on pokerstars

[aucubbie]

what is the best way to play this hand. I obviously played this hand wrong. Which would be a better way to play this?
middle in a tourney blinds 100/200 w 25 ante. I have 20k in chips utg with cleader at 22k in the bb. I have kt-s and raise to 400 utg (? play but i play agg. loose) everyone folds to the bb/chipleader and he calls. Flop 638 2hearts. I have a flush draw. cleader checks I bet a pot size bet 1k and he checkraises to 2k. I call and the turn is the 6 of hearts. I have the k high flush. cleader checks, I bet 2400 and get checkraised to 4800. I think about it and push all in for another 13k and he calls with full house 3over 6's (he had 33) I lose and knocked out the tourney. How can I play that hand better? assuming I still play the hand. Thanks