A while ago I read Will Hartzell-Baird’s Death Mill Mansion http://www.amazon.com/Death-Mill-Mansion-Lighthearted-Comedy-ebook/dp/B00408ANA0 and was impressed with all the plots and details he kept track of throughout the book. In really fun and interesting ways, he would bring back characters and plot devices that I had completely forgotten about.
I often wonder how great authors keep track of all their plots and subplots. Recently, I came across one answer to that question. Open Culture published a post with a picture of a page of one of J.K. Rowling’s plot charts for Harry Potter. http://www.openculture.com/2014/07/j-k-rowling-plotted-harry-potter-with-a-hand-drawn-spreadsheet.html
The rows keep track of your time within the story and the columns hold info for your plot and subplots. I created my own version on a spreadsheet: https://docs.google.com/spreadsheets/d/1H-yVz0Y5g7rLwKtEqFisArAMaNnzS3Xp4BWVWhhWOAs/edit?usp=sharing