I assume you're speaking of lightly ozonated olive oil? If so you're right, it will not be as strong as last year because all of the molecules of essential fatty acids were not converted to ozonides since it was only ozonated a few hours. It will have some benefit, but it's hard to say how potent it still is. If the same oil had been ozonated fully, it would have as much nascent oxygen as it did a year ago if kept frozen or refrigerated, but since the lightly ozonated oil EFA's are just in the beginning of the process of being converted, the oil tends to lose its nascent oxygen more quickly.
If you want greater benefit than you're getting now with last year's oil, I would suggest you get a new bottle and use the older stuff for massage or oil pulling or as a general skin moisturizer.
hope this helps,