This is a common problem when it comes to randomly spawning things and your scene has collisions. I had a similar problem and its actually really easy to fix. Take a look at Stencyl's Tile API. I'm
assuming that the white parts is just background and not tiles correct?
Either way the fix is pretty easy.
Create two number attributes (CharX, CharY) then do the following:
Set CharX: 'X' of the controllable actor.
Set CharY: 'Y' of the controllable actor.
http://www.stencyl.com/help/viewArticle/47 (*NOTE: You will only need to use "getTileAt"*)
Then useing code blocks, you can check the ID of the tile the actor is on top of, if it does not = null, then kill the actor and respawn (Without taking off lives).