Place rhubarb in a large bowl. Pour sugar over top and stir to coat. Cover bowl and refrigerate overnight.
Place rhubarb mixture in a pot and cook over medium heat until tender, stirring frequently. Stir in pie filling and gelatin, and bring mixture to a boil. Pour into a shallow pan and allow to cool in refrigerator. When jelly is cool, pack into jars or plastic containers. Can be refrigerated or frozen.