In reply to GridNorth:
Your body is right, you can't expect to climb like you were 20 again.
My climbing partner and I had a 2:1 session with Steve McClure at the start of the year and discussed training and improvement plans. His advice was very specific to our current abilities and ages. I'm now 49 and have been climbing for almost 17 years.
Steve recommended not climbing more than 3 times a week, and emphasised being fit and maintaining that fitness and specifically not getting injured. At our age (and presumably more so at yours) rest and recovery is almost more important than the actual time spent training. If you make sure you make the most of your training sessions and use your time efficiently, there's no reason why 3 sessions a week isn't sufficient to continue to improve.
You've not mentioned the levels you currently climb at, or if you boulder so this will probably influence how you might best seek improvement. The older you get, the more suited your body will become to endurance routes rather than shorter more powerful ones. It's a gradual decline in men I believe from their mid 20's, but don't quote me on that. There are several really decent training books out there and I recommend you try some of them.
'The Self Coached Climber' and
'9 out of 10 Climbers' are probably the two best known. I suppose it also depends on where you want to improve; is it trad routes, sport routes or bouldering? You have to tailor your training to suit your target(s). From my experience, most climbers don't
really train, they just climb - admittedly sometimes a lot - and assume it's the same thing. It's not. If you really choose to apply yourself and are serious about it, there's almost certainly no reason why you can't improve. A word of warning though: you do have to be ready to embrace the boredom and a certain amount of short-term pain
I'd also strongly recommend doing what I did and have a personal session with a decent coach, it'll be money well spent.