What type of stain to use over solid brown color stain

I have a solid stain on my covered pine treated 15 year old deck, that I got from walmart or menards. I have washed it with a homemade cleaner, bleach water and powder detergent. Then pressure washed off. No stain was removed. Next I rented an orbital sander, and it got off about 1/4 of the stain, but did nothing for in between the boards. Next I rented an edger sander, which was very aggressive, but did a better job, but was not good around nails or in between boards. I then tried a chemical paint and varnish remover, left on 15 minutes and scrubbed with a brush, only got a little of the color off.

My question, If I cannot get all of the stain off, What is the best stain to use on my deck? I wanted to get twp 1500 in a semi-transparent. Will this work or will I have to get another solid stain?

Also do you have any suggestions on how I can get the rest of the stain off my deck?