Hi… Were you using the Launch UI? As far as I know, that’s still considered experimental, and I doubt that it supports Git submodules.
In general, you shouldn’t put too much weight on having a particular app name, but you can try fly app delete followed by fly launch --name—and see if that gives the desired result.
If it’s a public registry, then fly deploy --image will work, but you will need the fly.toml first. (That file isn’t really that hard to create by hand, incidentally.)
If it’s a private registry, then you will need to copy it over to registry.fly.io first.
Hope this helps a little!