In a mixing bowl, mix together cake mix, guava juice, eggs, and coconut oil until well combined.
Bake in a 9x13 glass baking dish according to cake mix package directions.
In a medium mixing bowl, beat cream cheese with hand mixer until fluffy.
Add sugar and vanilla and mix well.
Slowly fold in the Cool Whip and refrigerate until ready to use.
In a medium saucepan, bring the 2 cups guava juice and sugar to a boil.
Make a slurry out of the cornstarch and a small amount of water.
Remove guava juice from heat and stir in the cornstarch mixture.
Return to heat and bring back to a boil and boil for one minute. Cool in refrigerator.
When cake has cooled, spread cream cheese mixture evenly over cake.
Glaze the top of the cake with guava gel. Refrigerate until ready to serve.