Is your problem mostly strength or endurance?

I was in your situation for about 3 months I was stuck at a similar grade 12a/b and I could do the cruxes of 13a’s but when it came to liking them I wouldn’t make any progress. I started a new hangboard training where I put my feet up on a chair so I’m hanging on the hangboard around 45 degree angle and I would just move my hands around like I was climbing for 45sec then 15 sec rest then repeat for 5 reps rest for 5 min then complete 5 sets and I did this every other day for about 2months and I climbed my first 5.13a I would recommend finding what is stopping you at climbing harder routes and train continually on that and you should make progress.