Bake your cake according to the package instructions, and then let cool for a few minutes.
Mix lemon jello with 1 cup of boiling water and stir till gelatin is dissolved, then mix in the cold water.
Poke holes in the cake using a skewer or large fork.
To make the raspberry sauce, in a sauce pan, combine the raspberries and jam.
Stir occasionally over medium to low heat, till the mixture is nice and thick and combined.
Chill this sauce while the jello cake is chilling.
Then spread out the sauce over the top of the cake.
Finally, cover it all with the whipped topping, and chill till you are ready to serve.
Refrigerate any leftovers.