After an excellent campaign which ended in a 14th-place finish, eight points clear of relegation, Leeds United’s hierarchy are happy with the squad’s floor — the focus ahead of their second season back in the Premier League is on raising its ceiling. Losing key players this summer is not on their radar.The principal aim for the coming transfer window is to turn over the fringes of the squad and replace those who do depart with difference-makers in attack, plus extra depth both in central defence and at wing-back. The goalkeeping picture, with Lucas Perri ousted as No 1 midseason and his replacement Karl Darlow’s future uncertain, remains up in the air.Pascal Struijk’s future is one item on the agenda which Leeds lack control over.The 26-year-old defender’s contract expires in 12 months. If he does not want to sign new terms, it is clear Leeds will have to sell him before the window closes at 11pm UK time on September 1. If they don’t and Struijk sits tight through his final year, the club would watch a valuable asset walk away for nothing as a free agent 12 months from now.As someone who arrived for a pittance from Ajax’s academy at age 18 in January 2018, Leeds have invested too much time and money in Struijk to forego the income that would come with any sale. And if the Dutchman indicates he feels ready for a new challenge, they will hope to receive a fee befitting a left-footed centre-back who has made 119 Premier League appearances across his four top-flight seasons and is popular in the dressing room.Replacing, and ideally improving upon, Struijk is of paramount importance if he does move on. In the three-centre-back system which served Leeds so well last season, he was ideal on its left side. Ladislav Krejci, relegated Wolverhampton Wanderers’ 27-year-old, left-footed centre-back currently playing at the World Cup for the Czech Republic, is one defender admired at Elland Road.