When retracting a delete vote, the following popup is displayed:
To quote the text directly:
Retract your vote to delete? You won't be able to vote again on this post.
This, however, is inaccurate, or it's at least inaccurate for me, right now. Your delete vote can be retracted and reapplied on answers only (delete votes on questions behave normally). This is just a formal request to have this fixed, as the ability to vote to delete and undelete was changed to only be allowed once per post per vote type.