Spicy margarita jelly not setting up
All gelling agents work only under certain conditions. You need to be in the working range for: 


temperature
sugar content
pH
alcohol 


Pectins are more sensitive than gelatine, working in narrower ranges. Also, not every pectin is active in the same range, the main difference is between HM and LM pectin. 

You can try if gelatine works with your recipe, but here we get into shelf life problems. If you wanted a refrigerated jelly, gelatine is OK. But if you want a jelly that is shelf stable after canning, you need to have at least 33% sugar by weight, better more, and as far as I know, it won't work with gelatine (I don't know if this is because of food safety consideration or because this is outside of the gelatine's working range). 

The better way is to find out what changes to make to the recipe in order to have the proper ranges for pectin to work. Use this table for the pectin properties. 



(source: Texture by Martin Lersch)

If your pectin type was not on the label, you're more likely to have HM pectin. 

I don't know whether trying to reprocess your current batch of jelly is worth it; it may or may not work. You have to calculate the risk (do you see it violating some of the conditions on this table?), your time, and the cost of the ingredients. Also, you don't say how much sugar you used, but if it was too little, it is not edible after 2 weeks in the fridge.