I agree just do the same as last year maybe re arrange things! A haunted walkthrough would be cool as well you can use what ever props you have!Do you still have all of last year's props and décor? If so, just repeat! If they loved it last year, they'll be excited to see it all again.
If not, how about a creepy spider theme? Tons of webs everywhere, which are super cheap, and some creepy lighting. Play a spooky soundtrack and you've got instant atmosphere for very little money. I definitely would not try to top last year with all you've got going on. No one needs that stress. Just have fun!