How do you refinish wood cabinets without painting them?

chec out old English scratch cover. It is a dark shade and semi penetrates the wood. You could scrub with fine steel wool, clean with TSP, and stain. Perhaps with a product that is stain and finish in one. I used one of those on my laundry room cabinets.

You can stain over stain with gel stain. Ant good brand will do. You can go darker but not lighter.

https://www.minwax.com/how-to-finish-wood/change-stain-color-with-polyshades/

I used Java gel stain on my oak cupboards. Just clean the cupboards and apply.

This is the best product that I have found. It really works and gives a nice finish. I have used it on cupboards, a desk and a dresser. I got mine at a specialty shop but it is available at Amazon as well. A little goes a long way.

If the wood color is light then restraining darker is probably the easiest way to go. Otherwise I think Behr makes a paint or cover that when out on makes the wood a natural color and then you can pick whatever stain color you want. Applying this cover with a brush creates the wood grain. Talk with someone at home depot in paint dept. They will tell you everything you need. I painted a plaster bust with this and it ended up looking like it was carved from wood.