Keep the original whatever you do, nothing is worth losing good, complete, work.
I agree with Cyn here, if your story takes 1500 words to tell then it does and that's all there is to it. Having said that if you have to try and cut a third out I would take a different tack.
To work out what you can cut, don't look at the narrative you've written, not as a complete collection of words anyway, instead look at the story in terms of conveying meaning. Cut the story down to a series of "what must be said" statements, this lets you see what passages convey the meanings and events that the story is built on and where you can cut content or indeed whole passages that don't directly serve the narrative. I can't give you a full example without including a large narrative passage but here's an example of a mismatch that I hope is demonstrative:
What must be said (the meaning goal of the passage): Spot is a dog.
Sample material that is irrelevant to that goal; "See Spot run, run Spot run."
A passage about Spot's running activities in no way tells us his species; as such we can cut it.
I've done this to narratives when trying to get material from disparate writing sessions lined up into a cohesive whole. It was amazing how little of the overall word count I actually needed to tell the bare bones of the story and how much was window dressing. I kept most of the window dressing because I didn't have a word limit but you can ditch it all and then pull back pieces you love that you can fit in.