It is easy for a story to lose focus, especially one you have been working on for quite a while.
Here are a few suggestions to try and pare it down and regain some focus:
First, go back to your original one line premise–ONE line that tells someone what the story is about. Ie: A woman escapes her past by climbing mount Everest, only to find love while trying to stay alive. Simplicity in this sentence is key.
So, in the above example, the entire story should revolve around this woman and that journey. If a martian shows up somewhere, there’s an issue. If there’s a ton of background info that doesn’t move the story forward, cut it. If your time line suddenly stretches out longer than you need it to make the story flow, condense it. There should be no fleshy stuff that doesn’t: let the reader know more about the character and what motivates her, move the story ever forward toward its natural conclusion, or show growth and continual development
Second, go chapter by chapter, and use ONE line to say what happens in that chapter, and then answer this question–if I take it out, does it make a difference to the story? Can the story still be fully understood and appreciated if it goes? No matter how lovely it is, if it can be taken out and make no difference at all? it must go. Or, alternatively, make it matter–add in something new, something that makes the section indispensable.
So, in the example above, if you have a memory sequence about a wonderful moment with the woman’s dad, who is still alive and caused her no emotional baggage, and it doesn’t reveal anything new about her personality or her reasons for climbing a big damn mountain, then cut it out. But if she’s reminiceing about that nice time with her father when she has cut him out of her life completely and realizes that she needs to make amends with him if and when she gets off the bloody big mountain, then that works for the story.
Last, try a story arc. Begin by drawing an arced line on a page. At the base of one end, write a sentence about your beginning: ie woman gets into massive fight with boss. Then, move along the line writing the next scene and the next, like lines of the alphabet. A leads to B leads to C, etc. At the highest part of the arc is your climax, the turning point of the novel where realizations are made, revelations come forth, etc. Then, as your curve downward on the arc, you begin resolving the issues, dealing with the revelations, tying up loose ends.
Example: A.our woman gets in a massive fight at work. Comes home to find her home burgled a fifth time, and her cat is dead of old age. B. Makes a decision after speaking with friends and getting drunk to toss it all away and go on a trip. C. she arrives at the airport in Nepal, feeling calmer, clearer, ready for the challenge but still not knowing what she will do when it is over, as she cant see life beyond it. D. Her Sherpa is female, hot, intelligent and wickedly sexy, but stubborn and refuses to talk to her. E. They struggle with their own demons as they struggle against the terrain, learning to depend on one another. F-Pinnacle: An avalanche and white out conditions dictate emergency treatment for one of them, and they end up having sex with lots of clothes on. They talk about their pasts, their hurts, their hopes, their crushed desires, only to rekindle those hopes and realize new desires. G. The white out passes, they find a way to tunnel out of the avalanche. They make a bizarre sled type thing to get the injured one back to safety, spending a few more nights learning about one another and cementing their budding love. H. They make it back to help, and although they never made it to the top of Everest, they’ve found one another. I. HEA that ties up loose ends, leaving them together and facing a bright future somewhere in Nepal. This is the last place on your arc, the end.
Here is a decent, if simple, example: http://kalkion.com/userfiles/Story%20Arc%20Diagram(2).gif