Loss of magic? Or tolerance?

Well... when i smoked waay more than now, i used to have problems to sleep if i didnt smoke. Do you drink stimulants like cofee, or coke/pepsi/whatever often? If so, maybe they are interferring with your sleep pattern, so you only can sleep because the stoning effect of thc. In this case, drinking this things only at morning/afternoon can help a lot.
Anyway, im sure a break of 3-4 days will make you very stoned. Try a small break. If it dont work enough, try a greater break (1 week), until you find the best duration for a break.
Last year i used to smoke twice a day, and the effects were not sooo high... then after the break i did, i only smoke once a day, and it makes a GREAT difference... now my higs are FAR higher than when i smoked twice a day... and i feel better too... more alert, and less burnt... moderation is the key.

Yea. What to do is, smoke a weekend, and then break that whole work week. If you need, take a couple shots (preferably) or a couple hits to get you to sleep. When Friday hits, buy your normal amount and smoke with some buds and just chill all night. You WILL get high. 4 days is great. And as others said, 2 weeks, a month, two months also add some to it, although the first few days of break lower tolerance the most.