Can I reactivate a chemoluminescent reaction?
Short answer: No, you can't! 

Longer answer: Still no, and this is why: The reaction between the oxalate and hydrogen peroxide is irreversible. Both compounds are consumed in the reaction and there is no way back! 

The only compound that survives is a fluorescent material, that absorbs in the UV, emits in the visible range and gives the colour that you finally observe.

As Ben Norris pointed out in his comment, your only options are:


add fresh diphenyloxalate and hydrogen peroxide (which again will be consumed) or
irradiate the fluorescent compound that has survived with a UV lamp