Hey, here's how I would do it:
Guitar into some input on the Apollo, then out of the Apollo into the re-amp box, out of the re-amp box to the amp with the OX. Then out of the OX into the Apollo. Here's how my connections look:
https://drive.google.com/file/d/1-lX50YKj70x-wBcMHGKUSW5VMbupdouQ/view?usp=sharingIn your case where mine says "MADI 7" in green yours will be whatever input you've plugged your guitar into. Where mine says "MADI 19" in blue yours will be the output going to your reamp box. Finally, where mine shows two microphones going to MADI 17 and MADI 18, when using an OX instead of mics it'll be the OX outputs going to whatever inputs you're using on your Apollo. The monitor connections on MADI 51 and 52 in my screenshot correspond to your speaker outputs.
Hope that helps!
Dean