If you are currently scoring at 47 I would recommend to brush up at the 600-700 level first by going through the questions on this forum and carefully attempting to understand the very valuable posts by some of GMC users.
Afterwards I would recommend you to practise the harder questions of the GMATCLUB CAT exam. If you happen to be weaker on some areas (i.e. DS), you might want to focus on that area by for example going through the DS book of Veritas Prep (does contain very valuable explanations on questions, although there are not too many hard questions).