All reviewers, regardless of their participation, receive an approval request when the rework is finished.
For general information check the Approval Phase.
Approved or disapproved
Approve the rework if you are confident that the comments are correctly reworked. You should be able to say from your own perspective that “I agree with the rework which is performed and I agree with the author’s reaction on the rejected comments.”
When you do not agree with the performed rework or with the reaction of the author, notify the moderator. When doing so, state clearly why you disapprove and what you expect to be done to get it approved.
Result of a disapproval can be a second rework round or a decision not to fix it. In all situations both the reviewer and author should feel OK with the decision.
I did not have comments, should I still (dis)approve the rework?
Yes, definitely. The document (which you already considered being “perfect”, since you did not have review comments) is reworked, so it might not be perfect anymore! So, even though you did not have comments, you still must approve or disapprove the rework.