S. R. Faruqi:

ho = ho kar
:tar;h-kash = schemer; imitator; conquered; vile

In this verse Mir has placed the word :tar;h-kash in such a way that ghazals and ghazals can be sacrificed for it. Talib Amuli has rightly said that 'a fresh word is equal to a theme'. The meanings of :tar;h-kash that I have indicated in the notes are all operative. In addition to them there is the meaning of 'mimic, player, actor' [naqqaal], and that too is not inappropriate.

The phrase :tar;he;N badal ga))ii;N too is also fine, because in addition to 'the styles changed', 'the circumstances changed', etc., its meaning can also be connected with :tar;h-kash -- that he adopted many new styles and devices for showing passion, but there was no result.

FWP:

SETS == SUBJECT?
MOTIFS
NAMES
TERMS

The word :tar;h is indeed the pivot of the verse, in all its various senses; so much so that the verse does a kind of word-exploration of its possibilities. It works well with the two refrain-occurrences of nah dekhaa , the first applying (metaphorically?) to the speaker, the second (literally) to the beloved.

Or at least, so we assume. But in fact, the only subject the verse actually provides is the un ne , that respected person who 'did not look in this direction' (or of course 'in that direction' would be possible, though with less immediacy). So the person who became perhaps (among many other possibilities) a 'schemer, imitator' of desire could be the beloved as readily as the lover. Then she might not have seen any effects of her fakery-- because, as we learn in the second line, she didn't bother to look for it. Or else the hapless lover himself might not have seen any effects of her fakery-- because even though she adopted new 'styles' or 'manners', she didn't deign to glance over and display them in his direction.