With so much negativity about child abuse and abandonment nowadays, perhaps employing the alternate ending of Ibsen's play in which Nora does not leave her children would better satisfy audiences.  Certainly, Nora can more easily leave Torvald and take the children along with a modern audience viewing, although her doing so may compromise the realism of the play for its time period.

Retaining the costumes of the time is important for the realistic aspect of Ibsen's play. After all, the problem of patriarchy and the femme covert laws is clearly within the Victorian Age, so depicting it through costumery is essential in order to convey this time period in order that audiences will accept the situation.  These same audiences are less likely, however, accept other realistic aspects such as Nora's leaving behind her children.

If you want to "contemporarize" the play, you might change the clothing to better represent the contemporary upper-classes, as suggested above. 

I agree also with the opinion that this play's commentary and subject matter remain relevant today and the text of the play seems perfectly understandable now.

Perhaps one exception is the inherited spine disorder of Dr. Rank. This doesn't make much sense to today's understanding of heredity, or at least his explanation of it doesn't. He believes that rich foods and "high living" on his father's part have given him a spine disease.  This could be adjusted, but doesn't need to be in order for the play to be relatable.

It seems the message ofA Doll's Houseis universal and immortal enough that the dialogue and relationships carry it in any era yet known to experience. Therefore one might change the setting, e.g., furniture, wall hangings, and the costumes, e.g., contemporary upper class clothes, without compromising the integrity of the play and its message. However I think changing the social class in which the action occurs would compromise the integrity of play and message.