Soft links are only linked to name of the file and not to the inode number. If the original file is renamed, the soft link is broken, and the link now doesn't know where it is pointing to. Posting this picture from one of the answers (which I don't remember, I saved this picture in my phone long ago) :
If the original file is renamed,
my-soft-link will point to a file name which no longer exists and hence will turn red as the link or the pointer will be broken. In such a case,
my-soft-link would be similar to a dangling pointer. It points to a file which does not exist.
On the other hand, there is no such problem in hard links because hard links point directly to the inode number. So if the original file is renamed,
my-hard-link will not become a dangling pointer.
So in order to reactivate your symbolic link, you can update your symbolic link by making it point to the renamed file.
ln -sfn test3 test2