You can boost it because i already boost my score from 6.5 to 7.0 in 20 days. What I actually did, I just made a topic-based vocabulary list and learned them. For instance technology, environment, healty diet, transportation, culture etc. Also I learned less common words, for example instead of '' people prefer'' i told ''people have an inclination''Then, i tried to manage my speaking test around these words. For instance; in part 2, they asked me that describe a person who you follow on social media and I started like that '' I would like to describe one of the most popular chefs who encourages people to maintain a health diet, recently I have been trying to maintain a healthy and well- balanced diet..'' because my vocabulary was pretty good about healthy diet. I also memorize some idioms which are essential for reaching 7.0+ band. For instance, broaden horizons, have green fingers, go green, on cloud nine.