Cerium (CeO) behavior in Glass Polishing?
My guess is that for the reason why your slurry deteriorates without chilling you should look the other way. Maybe the other slurry components are to blame? I do not see how ceria could impact the slurry performance in your case. Ceria (and yes, it's $\ce{CeO2}$ not $\ce{CeO}$) and some other oxides like zirconia are used in milling and polishing chiefly because of their physical hardness and chemical inertness. In other word, $\ce{CeO2}$ should probably be regarded as purely abrasive component. You need extreme conditions to chemically alter ceria, such as concentrated acids and a lot of prolonged heating, and the chemical interaction between ceria and the other solid materials is highly unlikely unless the temperatures are so high that the whole system starts to glow.