Hi Ram,
You could take 1 more CAT before Test Day, but I wouldn't recommend that you do any more than that. The fatigue that you felt after yesterday's CAT is NOT something that you want to have happen on Test Day, so you should not try to do that much work over this last week. Retaking a CAT that you've already used is NOT a realistic way to assess your skills.
There's no "magic" number of questions that you should be doing at this point. To push your score to a 740+, the bigger issue is your "precision" (how accurate is your work and are you still making little mistakes or "missing" key pieces of information/logic when dealing with a question). You can decide how many questions you choose to do, but the emphasis should be on making 0 silly/little mistakes.
While taking a timed Quant or Verbal section is fine, since you would be taking the section "out of context" (not doing the Essay and IR first), then the experience couldn't be considered 'realistic' nor 'test-like.' It would be decent practice, but the score result would likely be a bit 'inflated.'
Making some slight changes to how you deal with the entire Verbal section could make a big difference in how you score. The challenge is that you've already developed a series of habits for dealing with the Verbal section and you're likely not going to change those habits in 6 days. A good general bit of advice for CR and RC is that taking notes will help with your accuracy AND speed.
GMAT assassins aren't born, they're made,
Rich