Cranberry has no effect on THC. And all "detox" potions work because of dilution. That means they "work" because of the water that youre required by the instructions to drink with them. With the potion/water combo, all youre doing is diluting (thinning out) the THCA concentration that is present in your bladder. You are not ridding the body of THC, as the sales pitches would like you to believe.
The dilution phenomena is only temporary - once the fluids ingested had all been urinated out, the bladder is replenished with fresh THCA-laden urine by the kidneys - which explains the "increase" in your THCA levels.

In summary, detox products (especially the 5 day, 7 day detox and the like) are nothing but a big scam to capitalize on the so-called "war on drugs" by preying upon the uninformed and credulous, and taking their hard-earned cash. Cannabis users are victimized enough by the so-called "war on drugs" without the buzzarding, scamming detox product industry swooping down into the mix.

There is no product that can permanently rid the body of THC. The only proven way to permanently rid the body of THC is time and exercise.