Try using it. Sometimes water wakes up fragrances. If you are very tight on money, or simply want to try rebatching, feel free. This may be tough to melt down b/c it is so old, though.
I really like coconut milk for rebatching, I think it works better than water. Grate it finely and add enough liquid to moisten. Liquid options include water, veggie milk, and aloe juice. (Not dairy milk.) Let it sit overnight for the liquid to soften the soap.
Put it in a crockpot on low for 30 minutes without lifting the lid. (I know it's hard!) Peek and stir every 30 minutes or so. Add more liquid judiciously - a few spoonsful at a time. You can always add more, you can never add less!
If you have an FO that is not suitable for CP - perhaps it seizes badly or perhaps the fragrance morphs, try it in this batch.
I give away huge amounts of soap at Christmas. Honestly I'd give it away rather than trying to "save" it.