Level 55 requires a lot of attention on your part. It is best not to use the Lightning on the pieces of the same color as the chained ones as tempting as it might be. Instead focus on destroying the chains to make the pieces fall to the bottom part of the field creating auto-matches. As a result a a lot of tiles will be cleared automatically. If you use the Lightning, some pieces at the bottom row will be destroyed as well which will in turn would create empty spaces and make clearing the tiles even more difficult.
Be careful while using powerful power-ups as they might cause the same issue as the Lightning. Also, don’t worry too much about earth tiles and don’t forget about the tiles at the very top of the field.
You should also check out this video that shows how we got through level 55.