@jaxxon Do you have any other animals living in the house or visiting frequently? Are they on flea medication? Are you making sure you apply the medication directly to the skin of the dog?
How long before the end of the month are you seeing fleas again? If he hasn't had any sensitivities to Advantix at this point, it's not going to hurt him to apply it a few days to a week earlier (might hurt your bank, though). It is worth it. Fleas can carry disease, cause tapeworm infections and are very uncomfortable for dogs.
You probably don't need five spots, two or three should suffice (neck, mid back and lower back). Try to do it at a time where nobody will touch him and remove any of the the medication, it needs at least 1-2 hours to soak in completely and start spreading.
When did you first notice the problem and start using the Advantix? Sometimes it can take half a year or longer if you have a severe infestation. There are different lifecycles of the flea living in your home and eggs and pupae continue to hatch and emerge, which is why you need to keep them on a GOOD QUALITY AND EFFECTIVE topical medication EVERY MONTH ALL YEAR LONG. Don't stop if you don't see fleas! There may not be enough to see, but that doesn't mean they're not in the environment. By the time you see adults it's often too late and it's much easier to keep them on a preventative than deal with what you are now dealing with.
I don't know about Advantix's guarantees (I should look that up), but I think with Frontline if you have a record of purchasing it from your vet and using it for a certain amount of time and you're still having problems then they pay for an exterminator to check out your house. Just a thought to check with your vet about that and see if they know.
Where do you live? You may want to see if there is an area in the environment that may be re-exposing your dog to fleas. Regardless, if you're using the topicals and you still see fleas, the medication should at least kill them before they can lay eggs in your environment and perpetuate the cycle.
Also, frequently wash your dog's bedding and sleeping areas and vacuum. The Advantix is the number one thing I would keep doing, making sure to do it EVERY month (not late), but cleaning frequently couldn't hurt either.
I feel for you, flea infestations are horrible. If you need any more help you should contact your veterinarian for suggestions.
Normally I hate collars, but there has been a lot of good feedback from clients about the Seresto collar. It works like a topical medication and not like a normal flea collar. There is no odor or powder and it's very safe for people and kids, plus the pet wearing it. It's a flea and tick collar that you leave on for bathing and swimming and it lasts up to 8 months. You could try this or a combination of this and a topical to really try to blast the little jerks out of the water.
Good luck!