There is evidence that cannabis sensitivity varies considerably:
CONCLUSIONS: Genetic variation in AKT1 may mediate both short-term as well as longer-term effects on psychosis expression associated with use of cannabis, possibly through a mechanism of cannabinoid-regulated AKT1/GSK-3 signaling downstream of the dopamine D(2) receptor.
Whether one can sensitize oneself has not, as far as I can tell, been studied, but generally repeated exposure to a substance will desensitizes you.
Incidentally, cannabis is thought to be correlated with psychosis risk and other mild but measurable cognitive deficits (even when not high):
Compared to controls, cannabis users showed significant impairments on quality of decision-making (Cambridge Gamble task), and executive planning (One Touch Stockings of Cambridge task).
In the absence of evidence that all negative side-effects depend on the ability to get high (psychosis: yes; executive planning: I don't know), and in the absence of evidence that one could gain sensitivity, it might be prudent to avoid taking large doses for long periods of time in an attempt to achieve an enjoyable psychoactive effect.