I might have messed something up but I think you should be able to take it from here:

function split_season() { 
  S=$((($1-1)/$2))
  E=$(($1-$S*$2))
  printf "S%02dE%02d" $(($S+1)) $E  
}

EPISODES_PER_SEASON=15

for f in tv.show.*.mp4; do
  NUMBER=`echo $f|sed 's/[^[:digit:]]*\([[:digit:]]*\).mp4/\1/'`
  #maybe put echo at the beginning of the next line to test before moving?
  mv "$f" "Tv Show $(split_season $NUMBER $EPISODES_PER_SEASON).mp4"
done