Okay fellow space Roman's, what would be your plan for taking back lost territory?
I would sue for peace with the FWL with it hinging on trading control for captured systems.
Actually, negotiations could be beneficial in this situation. While Duke Fontaine Marik is in a very strong position, with lots of troops holding Illyria and other planets, his political front is not so strong, with the Parliament more focused in reintegrating Regulus, and facing the Wolves and the doorstep, and the Andurians and the MoC/Crapellans (even if the later are focused in the FS/RoTS). I can see the Parliament and the new Captain-General giving Fontaine the finger and making a deal with the MH only if the concessions are big enough to quell Fontains complaints.
Next push MoC off of the two systems in the east
I don't think the Canopians plan to stay long term in both planets. Sure, they will do a lot of damage to the local infrastructure bu damaging industries and freeing the slaves, but they are far from their frontlines, and the MH can hinder their logistical trains in the "empty" zone between the realms. Also, the MoC seems more focused in bullying lone ex-FWL planets and helping their Andurian allies.
Rebuild the Legions and begin making in roads with independent systems surrounding the Hegemony.
Personally, i think the best action, aside of rebuilding those Legions, its to focus in diplomacy with the minor planets and with the Lothians. Right now the bigger fishes in the pond (the FWL and MoC) seems more focused in other fronts, so its better not to alarm them by gobbling smaller entities.