If you do ever need to relist an item from scratch that's completely vanished off of eBay's servers then the best option would be to have a number of presaved templates available for all of the different items that you're likely to list on a regular basis. That way once you've set up the template all of the presaved information will automatically carry across to the latest listing, in which case you only need to delete the original photos and item description and upload some shots of the latest item being listed for sale, as well as including an item description written specifically for that item, and you shouldn't have to change the information in the Item Specifics fields that often, although you may do occasionally - for instance, if you need to amend your postage prices to reflect Royal Mail postage increases.
If you do need to make any updates to a presaved template then just save the template again once you've made the updates and the updated information will automatically carry across to the next listing you create using that template. If you do this when you list - or relist - items for sale then it will save you a lot of time when preparing the listings, as most of the work is already done for you and you won't have to fill in every single aspect of the listing form from scratch.
Finally, if you want to ensure that you can retrieve the listings again should the items not sell and you decide to relist them a considerable amount of time later prepare the listing on your computer or laptop, saving the item description as a Microsoft Word document and saving the document with a name that makes it easy to identify which listing it relates to. Do the same with the photos - save them on your computer or laptop and when you come to relist the item for sale again you can just pull up the template, delete the old photos and item description from the template and upload the photos of the item you want to list now, along with the item description that you wrote specifically for that item. I've done it myself in the past when I used to sell on eBay and it saved me a lot of time when creating listings, especially when I was listing a lot of items all in one go.
