Are you just moving your existing SCCM site to a new physical server but keeping everything the same? Or are you actually standing up a new site and migrating your users, content, collections, etc. to the new site? If the latter, I don't know that I have any customers that have tried that. Assuming all the applications, collections, etc. all migrate with the same ID's, then you may be able to simply change your SCCM settings in App Portal and then change the "Server" column on all the entries in the WD_SiteToAdvert table. However, if your package/application IDs, collection IDs, and advert IDs are all changing as part of the migration, then you'd have to come up with some sort of mapping between the old and new IDs and then update all of the relevant columns in the WD_SiteToAdvert table. @CharlesW would know better than I, but I'm pretty sure that WD_SiteToAdvert table is the only one you would need to change in order for App Portal to know which catalog items map to which SCCM objects.
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