How to raise the setting and melting point of gelatin

I have tried a variety of additives to gelatin in a range of blends and unfortunately, nothing seems to significantly increase the melting point. The additives I have tried include: agar, glycerin, corn starch, pectin, sugar, and corn syrup.

The melting (and setting) temperature of gelatine depends on the grade of gelatine. As per Wikipedia:

Gelatin gels exist over only a small temperature range, the upper limit being the melting point of the gel, which depends on gelatin grade and concentration (but is typically less than 35 °C) and the lower limit the freezing point at which ice crystallizes. The upper melting point is below human body temperature, a factor which is important for mouthfeel of foods produced with gelatin.

I would suggest experimenting with adding Agar to the mix, as Agar has a melting temperature of 85 °C, and sets at between 32 and 40 °C (again, as per Wikipedia

I would not "add" agar - I'd simply switch from gelatin to agar (or agar-agar if that makes it easier to spot at the store.) I personally find the powdered version easiest to measure/work with, but be aware that it also comes as rather large "sticks" that look somewhat like a clear dried noodle.

It's not a direct substitution - I generally use somewhat less agar than gelatin, and too much agar can be unpleasant, so some experimentation is probably called for when switching.

Chicken gelatin has a higher melting point than beef/pork

There are two answers that I can offer that may help, but you must test them yourself as I do not know if you are referring solely to gelatin or Jell-o.

Tip one: use 4 Tablespoons of beef gelatin powder for every cup (8 o.z) of hot liquid that you add to it to set. The larger amount of gelatin once dissolved and set will give you more a a "Gummy worm" texture rather than a Jell-o-like texture that can be spooned as in a dessert. (Which literally melts in your mouth).

Tip two: Is to make your gelatin from whatever animal source you derive from, let it set in fridge, then put in saucepan and let it reheat and reduce. Then reset the new gelatin as you would (whether in a mold or in a recipe). The new batch of gelatin will have a higher melting point because it is now more concentrated.

Bonus tip: (though I've never tried it) If you are referring to Jell-o type of gelatin. They used to have a recipe for "Jigglers." Never made, but they were also similar to a Gummy worm texture that can be held in your hand and eaten like candy. If that recipe still exists, it may help guide you.

To increase the melting point and solidification gelatin often combines with other hydrocolloids such as guar gum, xanthan and carrageenan.