In the case of oyster mushrooms I would suggest making sequential beds. As one bed becomes colonized but before it begins production decline use it as inoculum for the next bed.
With your existing bed I would check to see the vigor of the mycelium and to see if the fungus is still alive and viable. Place some wet corrugated
cardboard on top of an area of your patch, cover and keep moist. I soak the cardboard and separate it so you wind up with a corrugated face that you will place down. You should see mycelium running on the cardboard within a week or two. If indeed it is still active I would use some of the old bed as inoculum for a new one.
Oyster mushrooms colonize rapidly and yield well on chopped
straw. You can try adding a layer of hardwood chips and or straw in between flushes to “feed” existing beds. Denser substrates such as wood chips will result in longer lived beds. Lighter substrates such as straw will colonize and fruit faster build will not be as long lived.
Do your best to maintain moisture in your patch, even in the winter, Irrigating if necessary. Mulching with straw, card board or even a tarp can help ensure a patch will not dry out in some drier months of winter.
Remember oyster mushrooms are primary decomposers so when they are finished breaking down their substrate and fruiting, secondary decomposers, bacteria and insects move in to finish off the soil making process.
This is why I recommend using an active bed as inoculum for newer beds.
Other mushrooms like the wine cap stropharia and lepista nuda are more suitable for longer lived beds that can be fed to lengthen the life of the patch.
Hope this helps.
Be well, Dave