In the beggining of Every season the price of the players will decrease depending on age and training speed, and If you go up one level they also lose a star, but the Q is the same.
You need to have 14 players with contract signed at the beggining of every season.
If you do not need them, try to sell them now, but it is not easy selling low quality players on level 1, so you probably will be more lucky at the beggining of next season.