To my knowledge there is no way to do so. To be sure contact EVGA tech support. 

To kind of sum it up it is best to replace the AIO cooler if you notice that the temperature isn't what it should be and has greatly changed since it was first installed. It typically takes a very long time for these coolers to lose much coolant to evaporation through the tubes and it's probably better to just change it out anyway since the rest of it has probably been used close to the expected lifespan.