Seeking Advice to Improve My GMAT Score to 720-74

I'm feeling a bit troubled and could use your help. My goal is to achieve a GMAT score between 720-740, but I'm facing some doubts and confusion. Here's where I stand:

I've taken the GMAT twice, with these scores:

700 (Q48, V37) IR 5, AWA 5 - September 14th, 2023
640 (Q48, V28) IR 7, AWA - Still waiting for the result
My ultimate aim is to improve my GMAT score by the end of December to be ready for business school applications in January 2024, Round 2. However, I'm facing some specific challenges that have left me unsure:

Doubt About Improvement: I initially felt I could improve, but now I'm uncertain about what to do. Should I settle for 700?
A bit about my background: I'm an architect with over 5 years of work experience. I haven't had much exposure to quantitative subjects over the past 10 years, but my English is relatively strong. I started preparing in February and took my first exam in September. Admittedly, I didn't dedicate a lot of time to preparation for the second attempt because I thought I already knew the material. My official mock test scores were 710 and 680, taken just days before the second attempt.

I'm really perplexed about my next steps, and I'd appreciate your advice and insights. How can I move forward, considering my background and the limited time I have? What would you suggest?