Hi. Congrats on improving to 645! That's an awesome progress.
I would say the strategy is a bit different depending on the Q/V/DI direction you want to take.
I would focus on the lowest hanging fruit. What can you improve the most?
Since your quant section was easy - it seems you may have made some careless mistakes - perhaps that's worth focusing on for Quant, how to eliminate specifically careless mistakes in easy and medium questions (so that's one direction) not necessarily hard ones.
For Verbal, is it RC or CR 🤷♂️
For DI - is it DS or the other ones? There is a different approach for both. For DS, you probably want to focus on the underlining principles and try to focus on theory but in DI other types, it is all about reading the data sources and really practice is the only tool but you can study/review smarter so you don't just mindlessly solving millions of questions. You want to focus on the solution approach, eliminate mistakes and celebrate when you learned something - write it down - create notes!