Provided it is still alive at the moment I don't think I would worry too much they are pretty robust and do spread.

Arum lilies must be some of the most robust plants around. Ours had got into advanced growth this year in February, just when the intensely cold weather struck. They were completely blasted by the frost but subsequently came back and flowered as well as ever in May and June.
They love lots of water, so make sure they are not in a dry spot. They take a while to establish but you will be unlucky if you don't get flowers next year.

Thanks for you answers. It looks very healthy and has grown alot so hopefully will flower next year. It is not in a dry spot so i've done everything correct. Thanks