I have wood in the bottom of my buckets, so don't empty them completely, just take out a bit and 'revitalise ' it. In a year's use the level has dropped a bit anyway so I don't get a lot over. What there is I put towards new buckets.
I also try to vary what is growing in them, rotating crops. At this time of year, when my tomatoes and peppers are finishing, I have strawberry runners going in, late radishes in the greenhouse, carrots coming on and some leeks I am trying in buckets for the first time, I planted them in an almost empty bucket and have been filling it up as they grow instead of a trench and earthing up.
I found carrots very successful, no slugs or diseases, I stand them up a bit and carrot fly don't find them, which means I can weed and thin without waiting for rain or evening but you can't put many to a bucket or they stay small. I don't know what grows out of tomato season in your neck of the woods, but worth thinking about, fresh carrots for Christmas dinner.
