I haven't tested this yet but I think it will work and I'll tell you why later.

Many people have been whining about evil beings in their dreams and these being have an annoying advantage... To be immortal.

Why are your evil enemies able to go back to life and continue to chase you and keep you from doing anything fun? My own theory is "fright". You are scared that the evil being might still be alife. Just thinking about the possibility that he might still be alive with such a strong emotion gives them the power to be alive again.

What? You are not able to not be afraid and just forget everything about them? Well, I have my own little solution if no one has ever said anything about it... There it is

Just eat them!

You can eat anything in your dream so if you eat the evil being, it won't be afront of your eyes anymore. Conclusion: No worries of it being still alive, its not there anymore...

If you have this problem try it and tell me if it worked, I want to know.