You do not need to recharge your air conditioner until and unless the closed loop system has developed a leaq. If your air conditioner is blowing less then cold air, it might just be so that you may need to cool your system. If the problem still continues, then its best recommended to call an air conditioner specialist. Due to the ozone depleting pollutants in the refrigerant, it is recommended that you do not try and recharge your system yourself.