Updates, updates, updates! I can't stress that enough... and will continue to do so.
As someone who's contributed to several fundraising campaigns, on Kickstarter, Indiegogo, via Paypal, and elsewhere, and also as someone who writes about this stuff, I find it frustrating when the creators behind a project I contributed to, don't publish regular updates on their progress; this is after they've successfully reached their fundraising goals.
These don't have to be daily, weekly, or even monthly updates. But you really shouldn't let a lengthy period of time pass before you post an update via whatever crowdfunding site you used; specifically, updates on the project that your contributors donated money to. It's just courtesy, really.
I was inspired to write this because a project I contributed to in late 2015, which is not yet complete, and which I only just happened to think about while researching another project, hasn't provided any updates since spring of 2016! That's a year ago, and way too long of a period to let pass without sharing something with your donors. It doesn't have to be some detailed, comprehensive update; but at least let us know that you're still working on the project, and that the $36,000+ you raised is being put to good use. And if the project is dead, let us know that as well, providing some explanation as to why.
It could be a simple note to say "hello," accompanied by a few sentences about what's new with the project, if anything, or just where it stands, even if nothing's changed since the previous update. I'm a filmmaker myself so I understand; while in production, things can get a bit hectic, and updating your Kickstarter or Indiegogo contributors isn't exactly the first thing on your to-do list. And I also realize that there isn't always going to be something to update your contributors on. But, like I said, you don't have to do this frequently. However, it's ridiculous to allow a full year to pass without any kind of an update. I think that'll turn some people off, and may actually hurt your reputation if you plan to go the crowdfunding route for future projects.
These crowdfunding platforms rely on an honor system, so do your best to honor it.
And if you happen to be providing updates elsewhere - like on a separate blog, or maybe you've created a Facebook and/or Twitter page for the project - you should at least make sure to mention that on the page of whatever crowdfunding platform you use - Kickstarter, IndieGoGo, etc - so that your contributors know where to look and subscribe for future updates.
I'm guessing that many who contribute to campaigns don't necessarily follow the progress of the project they gave money to, and may even forget about it altogether. But there are those of us who do follow your progress, and really appreciate the updates, especially when they happen often enough, helping us stay abreast of how the project is moving along.
It's really not that difficult a thing to do; it's just courtesy, and good business! You don't only hurt yourself; you might be making it difficult for others in the future.