Is there a way to make your air conditioner cooler?

Clean out the back of the condenser coil on the outside unit, these are waterproof so just hosing it out will suffice. Also hose out the filters in the evaporator (head unit) you just pop the plastic fascia up and the filters will slide out... If they are dirty this can restrict the air-flow and reduce the cooling efficiency.

If they are already clean the unit may have lost it's refrigerant, there will probably be a oil residue located near the outdoor unit or the connections of the head unit if this is the case, or the sensor/mother board may have died... in which case you are better off getting a new unit as the companies charge through the teeth for parts and it's likely that the problem could have caused damage to the compressor or other components leading to further problems down the track, where as a new unit will have a warranty...

Fingers crossed it's nothing serious and good luck!

You can have a professional recharge it with freon. It does take a licensed professional to perform this task. If it doesn't need to be recharged all you can do is replace it with a newer or larger unit.