A mon avis il faut que tu redéfinisses tes texture dans la boucle principale
exemple

   irr::video::ITexture *SkyBoxtop = driver->getTexture ("top.jpg");
   irr::video::ITexture *SkyBoxbottom = driver->getTexture ("bottom.jpg");
   irr::video::ITexture *SkyBoxleft = driver->getTexture ("left.jpg");
   irr::video::ITexture *SkyBoxright = driver->getTexture ("right.jpg");
   irr::video::ITexture *SkyBoxfront = driver->getTexture ("front.jpg");
   irr::video::ITexture *SkyBoxback = driver->getTexture ("back.jpg");
   ISceneNode* SkyDome = smgr->addSkyBoxSceneNode(SkyBoxtop,SkyBoxbottom,SkyBoxleft,SkyBoxright,SkyBoxfront,SkyBoxback,0,-1);



int i = 0;
   while(device->run())
    {

        driver->beginScene(true, true, SColor(0,200,200,200));
if(i != 0)
{   
   SkyBoxtop = driver->getTexture ("1.jpg");
   SkyBoxbottom = driver->getTexture ("2.jpg");
   SkyBoxleft = driver->getTexture ("3.jpg");
   SkyBoxright = driver->getTexture ("3.jpg");
   SkyBoxfront = driver->getTexture ("3.jpg");
   SkyBoxback = driver->getTexture ("3.jpg");
   SkyDome = smgr->addSkyBoxSceneNode(SkyBoxtop,SkyBoxbottom,SkyBoxleft,SkyBoxright,SkyBoxfront,SkyBoxback,0,-1);
};
        smgr->drawAll();
        guienv->drawAll();

        driver->endScene();
    }

et comme sa dès que tu à besoin de changer ta skybox tu mets i à 1

A mon avis il faut que tu redéfinisses tes texture dans la boucle principale
exemple

   irr::video::ITexture *SkyBoxtop = driver->getTexture ("top.jpg");
   irr::video::ITexture *SkyBoxbottom = driver->getTexture ("bottom.jpg");
   irr::video::ITexture *SkyBoxleft = driver->getTexture ("left.jpg");
   irr::video::ITexture *SkyBoxright = driver->getTexture ("right.jpg");
   irr::video::ITexture *SkyBoxfront = driver->getTexture ("front.jpg");
   irr::video::ITexture *SkyBoxback = driver->getTexture ("back.jpg");
   ISceneNode* SkyDome = smgr->addSkyBoxSceneNode(SkyBoxtop,SkyBoxbottom,SkyBoxleft,SkyBoxright,SkyBoxfront,SkyBoxback,0,-1);



int i = 0;
   while(device->run())
    {

        driver->beginScene(true, true, SColor(0,200,200,200));
if(i != 0)
{   
   SkyBoxtop = driver->getTexture ("1.jpg");
   SkyBoxbottom = driver->getTexture ("2.jpg");
   SkyBoxleft = driver->getTexture ("3.jpg");
   SkyBoxright = driver->getTexture ("3.jpg");
   SkyBoxfront = driver->getTexture ("3.jpg");
   SkyBoxback = driver->getTexture ("3.jpg");
   SkyDome = smgr->addSkyBoxSceneNode(SkyBoxtop,SkyBoxbottom,SkyBoxleft,SkyBoxright,SkyBoxfront,SkyBoxback,0,-1);
};
        smgr->drawAll();
        guienv->drawAll();

        driver->endScene();
    }

et comme sa dès que tu à besoin de changer ta skybox tu mets i à 1