What makes you think you didn't bleach them sufficiently? Did you use separate bleach and stop baths or was it a single bath? If it was a single bath you could have a go at bleaching them again but I wouldn't hold your breath about the results though. If it was separate bleach and then fix and the film had been through the fixer then re-bleaching will not have any effect.
You were right... I tried re-bleaching the film and it didn't do much of anything. Again, I use the Flexicolor SM chemistry—the bleach and fix are separate. Could you tell me more about why it had no effect, and what I can do to prevent this from happening again in the future?
(For reference, here's what I'm dealing with. My hand-processed film is on the left, and the lab-processed film is on the right. Both are Ultramax 400.)