I just checked around various Pokemon sites including Smogon, Serebii and Bulbapedia, and none of them mention anything about the effects of trapping moves disappearing when the attacker switches out.
Basically, this means that either they all missed the information, or the effects do in fact remain and thus information on the subject was unnecessary and was left out.
I find it very hard to imagine that all three of these excellent Pokemon sites have missed such a small detail. Anyone who has an account on Bulbapedia could edit the info in, and Smogon and Serebii are so populous that the chances of them missing the info are incredibly low.
This does of course mean that I cannot give you a definite answer, but I am pretty confident that the answer is yes.
