Dive until you can’t or shouldn’t. Stay heart healthy (regular exercise out of the water) and know your limits. I’ve seen some danged old people diving (I mean really older than me even :-) ) I applaud your decision to get refresher training. I was taught that it was a must to get it if eve out of the water 6 months. Refresher never hurt even those who diver regularly because we all tend to get complacent at times and that could be a risky frame of mind. BUT mind you I am just spouting my OPINION. I am not a dive master or pro. I just believe safety first because I want to go home at the end of the day.