Replying to Bindings came off

I was greasing a rail on my set up and when I landed the heelpeice came off! Tried screwing it back on but it won't stay. Is there anyway I can use the skis and bindings again or are they done for good? I have a new pair and I'm getting them mounted today. I'm gonna be beating the hell out of them so is there anything I can do to prevent the bindings from coming off on my new skis? If you can anwser either of these questions please. Thanks.