I've changed them before - just because it seemed like a good idea! But today I refilled a tank with a carto that has been almost empty for several days while I waited for the juice to arrive. The vape seems thin, even though I reprimed the carto. Is this a sign it's time to change it? Anything else I've missed (more priming)? No dry hits, it just seems a little airy and - thin, if that makes sense?