If you don't hit your target you'll still receive any funds you raised (minus our small processing costs), so you can still make good things happen!
If you raise less than you intended you'll just have to rethink the scope of your project, or find a way to raise the additional money you need.
If you want to extend your crowdfunding project to give you more time to achieve your target, we have some tips on how to do that here
Also check out our article on tips to crowdfunding which could help boost your donations.