Hi Srinath,
Welcome to GMATClub!
The GMATPrep tests are a good indicator of where you stand now. Analyze your test and try and pin point your weak areas
From my personal experience, I strongly feel that you should use the
GMATClub tests(maybe use them for topic specific practice) - especially on your weak areas.
Also, the 700+ DS questions are laced with several traps(traps you didn't know exist) and doing these problems will definitely improve your understanding on how to solve DS questions
Working on your weak areas and fixing those errora will help improve your score drastically.
That being said, it would not be wrong to take the second test after a few days of practice
to check if the GMATPrep Quant score(Q46) was just an aberration!
Hope that helps you!