Well, there is a ceiling to the analgesic effects of codeine, usually around the 300mg mark. Anything over this will not really produce any more positive effects. So if your tolerance is over 300mg, I would suggest taking a break or switching to a more potent opioid (that is if you want to continue down the road of addiction)
But codeine is very relaxing when taken occassionally.
Also, you could try using carisoprodol (Soma) to potentiate it, but you would need to be careful. For some unknown reason, carisoprodol seems to potentiate the codeine-like opioids more so than the others. LOTS of people have died combining hydrocodone and carisoprodol so be careful.