Blocked Post-Completion-- advice?

Writing is not just about writing - there's also the thinky thing. I suggest you take a few days to rearrange your desk and office, clear the walls of any little stuck on notes and suggestions and put the pictures back, go and make a quite outrageous series of purchases at Officeworks (or where-ever else you buy notebooks and pencils and post-its) and then - and this is a very important step - sharpen every one those pencils yourself. I can't stress the importance of this enough. Then clean the desk again, and label all your manila folders and then give a fair bit of time to trying out different filing methods.

Avoid pushing it, is my advice. Be open to the new ideas arriving, but don't scare them off by hunting them down too aggressively. Let them appear, disappear and reappear. Then grab them.

Good luck! Pace yourself. Don't forget a jar full of black jelly beans will see you through most dilemmas.

I love the phrase "Let is marinate". That's what I think you need to do. Realize that just because you're not writing RIGHT NOW, that doesn't mean you're not working on your writing. Sometimes, I don't write anything for days, or even weeks, but I'm constantly thinking about my writing, what the characters should do next, what changes I can make to improve the story, etc.

The key here is acceptance. Accept that, no, you're not going to write anything right now. Relax. Read a lot. Watch those movies you didn't have time to see while working on your manuscript. And while you do that, let it marinate. When the story's done, it'll come to you.

Have you been partaking in other people's art? Meaning not just books, but music, television, or paintings?

No clue if you're the same, but I personally can get a lot of inspiration from those things.

I recommend going to a bookstore and going to the photobooks and interior decorating sections. Just staring at pictures of landscapes and various types of rooms really loads up and inspires the brain. It makes you think about who would live in such a room, or what you would do if you lived in that room.

...Okay, fine, I like to look at well-designed rooms and pretend I live there. But seriously, it's a fun, re-charging thing.

I always think I'm going to take a few days or more off after finishing a novel to clear my head. When I'm in the middle of it, I may as well be on another planet. But then inevitably the next day, I am working on something else. I think I have one of those old disc changers in my head. One ends, and the next one starts. No idea. It does help as others have said to pick up a new book, or watch a new show, or go walking/biking. That helps clear my head. I always have a few different ideas going, and it's good to always have something else going because inevitably you will be stuck. Right now I have been on about a six week break from a WIP novel I started in March. I got almost 400 pages in and it just bogged down. I needed to step back and reconsider where I was going and what I wanted. I'm still sorting it out, but in the meantime, I've been writing short stories and tinkering with other books.

I know for me, at least, writing a story is a little bit like have a baby. You've cared for and nurtured this story for however long it took you to write it and then suddenly, it's been sent out into the big wide world, and you're still there, with an 'empty nest'. I find that I need to give myself a week or two to wallow in the story that is finished to find my way to let it go and close that book. It's only once I've done that that my brain is ready to consider other ideas - even if I had the ideas lined up before. I just can't stop one world and enter another in an instant.

So be kind to yourself, go out and do stuff and don't think about writing at all. When your brain is ready, it'll throw ideas at you.

Advice is good, but no advice is one-size-fits-all. Do what works for you.

In other words, +1 to the other posters' excellent advice.