Several people have asked me about conclusions for IELTS Writing Task 2. The main body paragraphs are much more important, so don't worry too much about the conclusion; make it short, simple and fast.
Here are some example conclusion phrases for different types of question:
For the reasons mentioned above, I believe that... (+ repeat your opinion).
2. Discussion (+ Opinion)
In conclusion, there are convincing arguments both for and against... (topic), but I believe that... (if the question asks for your opinion).
3. Advantages and Disadvantages
In conclusion, I would argue that the benefits of... (topic) outweigh the drawbacks.
4. Problem and Solution
In conclusion, it is clear that there are various reasons for... (topic), and steps need to be taken to tackle this problem.