Its like if first you make the skeleton of the story and when you put the last bone you start adding the flesh, the nerves, the blood, etc. That way when you finish the heart of the book can start beating. (creepy example?)

Make sure to read your book several times, you will see that each time you read it you will find a new thing to add, like a joke, a clue to the reader so he can try to guess whats going to happend and many more things.

You can also make a copie of your book and give it to a friend or a family member so he can read it and give you another point of view of it and were it gets too complicated.

I think the rewritting its a long proces but also can be fun.

Happy writting!

Hari

I wouldn't make it longer just to make it longer. I'd focus on exploring the conflicts, and would interpret "make it longer" as "there's room to explore the conflicts".

For me, "exploring the conflicts" would probably mean making character motivation more clear, and resolving conflicts actively rather than passively, with action and dialogue instead of infodump.