Some say that using a candle for more than one spell can scatter your intent, some say that a cleansing and rededication can cancel that out, and your own path might have specific guidelines on what to do. Personally (solitary eclectic) I'd cleanse them especially if it's a big candle that you can get a lot of use out of. Salt water and/or sage smoke will be fine, and visualise it being completely cleared of it's old intention. When you're rededicating it, which is basically just the anointing you would have done anyway, put extra energy into defining it's new purpose and all should be well :)
Re: candle use
By: Misanthropy Moderator / Knowledgeable Nov 11, 2016
Post # 4
You can. Whether you do or do not is really up to you. Personally, I always reuse mine, if there is still a good bit of the candle left. For example, if I am doing a candle spell for protection, I will reuse the candle, since I have already charged it with that particular intent. I find it saves candles (and money) if I reuse a candle that still has a lot left to burn on it.
I usually purchase the taper candles or seven day candles for this reason. I can charge them with my intent and reuse them multiple times, until they completely burn away.