Good morning!
If you are talking about a Five Pawns juice... I would suggest working with a smaller amount before changing your whole bottle, unless you don't mind waiting to find more / buying another bottle if you make this bottle un-vapeable.
Sadly, adding anything besides more of the same juice is going to alter the flavor, but I suppose a weaker flavor is better than a juice you don't want to vape.
I would suggest adding a premium spirit to a small amount of the juice to increase the throat hit. Perhaps a spirit that you have sipped while vaping, maybe a Scotch or Irish whiskey. This should up your throat hit (if that's what you are really looking for versus nicotine) and it would stick to the spirit of the juice flavor, but it will effect the overall flavor.
Either way, I would like to hear your results for whatever you try
Side Note: After seeing how Five Pawns let's their juice sit in those cute little barrels, I have wondered if it really imparts any additional flavor... also wondered if they are using reclaimed wood from whiskey barrels etc. or just starting with fresh wood and making the barrels like the whiskey/liquor companies do.