S. R. Faruqi:

The verse is commonplace and is by way of introduction. But the use of the word āṡār is not devoid of interest. One of its meanings is 'foundation' as well. The 'breadth of a wall' is another; among builders the word is still used in this way. For more detail see farhang-e iṣt̤ilāḥāt-e peshahvarāñ vol. 1, by Maulvi Zafar ul-Rahman. Thus the word āṡār , here and in {233,1}, is a zila with 'door and walls'.

In urdū luġhat , tārīḳhī uṣūl par , vol. 2, the present verse has been noted and the meaning given as follows: 'That survival (writing, building, or framework, etc.) from ancient or former times, through which information can be obtained about the history and culture of its era; remainder, memorial'.

It's clear that all these meanings are only imaginary, and are entirely without connection to this verse. Here āṡār is used in its common meaning of 'traces', and with regard to the builders' term it's a zila with 'door and walls'; and the beauty of the verse too is in this very thing. Otherwise, in the first line the refrain would not be fully effective [kār-gar], and although the theme is comparatively new, its expression would be without 'proof', so that there would be no special beauty in it.

FWP:

SETS
MOTIFS == [DEAD LOVER SPEAKS]
NAMES
TERMS == PROOF; ZILA

SRF is usually a great finder and defender of secondary and tertiary meanings, so it's salutary for him to remind us that such meanings can sometimes be over-emphasized at the expense of the primary meanings, the ones that are truly activated and effective within the context of the verse. Over-reading, or hyper-expansion of meaning(s), is a morbid practice that should be avoided as carefully as possible.

In the case of this verse, however, if we wanted to argue the point we could maintain that in the verse we don't know how much time has passed since the speaker/lover's death-- perhaps he died ages ago, but through the miraculous power of passion, his blood is even now moist on the doors and walls, so that the bloodstains not only are 'traces' but also constitute a 'memorial' or 'ancient survival' that provides testimony about the long-ago lover's way of life (and death).

Note for grammar fans: In the first line the se is not the postposition, but is short for jaise : there are 'things like' āṡār .