I appreciate you trying to save your plant, and here are my 2 cents
Spider mites hate water. You can take a hose and spray a forceful and hard stream of water to every inch of the plant, leaves, stem and all, fully and thoroughly. When finished, thoroughly wash the ground to remove any spider mites which would have fallen to the ground. This will take care of the adult mites but not the eggs, so you will have to repeat this 2-3 times every 5 - 6 days to get them too. Do it once more if you think the problem persists. Neem oil treatment can also help kill the adult spider mites, and you must repeat in 5-6 days to kill of the freshly hatched eggs and larvae too.
Also, when I prune my hibiscus plants, I usually keep 2/3rds of the main branches and cut the rest off. I also remove the weak or sideways growing branches. If the plant is only a foot tall, I think it would be good if you pruned the main branches only to about 8 inches and removed the side growing and weak branches entirely.
As a footnote, I am no expert on hibiscus care.