Let’s say I call up a god/spirit using a candle and then a week later I want to call up the entity again, do I use the same candle or do I have to use a new one?
I would say, same entity, same candle, the only thing to avoid is taking one entity’s items and using them to call up a different sapirit, unless they’ve given you express permission.
If the candle is a vigil candle, yes you can do that. Anything smaller and you need a new one. Also, don’t forget to load it with herbs and oils. Tea lights like this are the best.