If you could smell your wax melts earlier but barely notice them now, the two most likely explanations are fading fragrance and getting used to the scent. Those need different responses, so check before adding more wax.
Leave the scented room for a while and return. If the smell is obvious as you walk back in, the wax is still releasing fragrance even though you stopped noticing it during continuous exposure. Someone who has just arrived may also notice it more easily. You do not need to keep increasing the strength to make it noticeable every minute.
If the portion has already been warmed repeatedly and remains faint when you return, let it cool and replace it as directed. Use a familiar scent in the usual amount. If the fresh portion performs well, the old wax was likely ready to be changed.
If fresh wax also seems weak, consider the setup. Has the warmer moved into a larger room? Is a fan or open window changing where the fragrance goes? Is the dish seated properly, and is the warmer operating according to its instructions?
A fragrance can be subtle without being defective. A soft wood or musk blend may register very differently from a sharp citrus or sweet fruit scent. Try a different fragrance you already know before deciding the warmer or an entire pack is the problem.
Make one change at a time. That gives you a useful answer and avoids using up several cubes while the real issue is the room or your familiarity with the scent.