If there are particular levels that you can’t complete, try replaying them. You will get different drops each time you play and you will eventually be able to beat all levels. It might prove to be a bit frustrating, but it’s doable if you are patient and strategize a bit when it comes to the matches that you make.
Try to focus on elements:
Try to ignore one type of elements for a couple of matches in order to allow for that type of element to fill the board and therefore make it a lot easier for you to create a super-lengthy match, which will give you a lot more thanks to the bonus. Also, try to match one or two types of elements in order to allow the board to be filled with what you need.