Oh I know there are issues. I just thought it would be a cool thing to have this floating derelict marking the site of a major battle. Even in their current implementation, Titans are a huge victory if you bring one down. It's really a pivotal moment. It would be thematically interesting to have a marker of such an event, even if from a gameplay standing it has no utility.
There needs to be some mechanism of diminishing returns. Successive Titans should be more costly. If you retain the XP gained, that's fine. But without disincentives you will throw them into unwinnable battles just to grind levels off of overwhelming enemies. Titans need to either increase in cost each successive purchase (a fair trade-off). Or lose XP per 'resurrection'. Persistent XP is f
I think when a Titan dies it should leave behind a carcass. A wrecked version of the ship model floating in space. I don't know what attributes or gameplay elements would be attached, if any, but it would be a cool monument to a pivotal battle.
Kick the XP persistence to the military research tab. Make it off by default, but researchable. Create some kind of new research called, I don't know, 'Persistent Doctrine'. Have it cost a lot of resources, be tier 8, and have three ranks. 30%, 60% and 100%. So that if you put in a lot of money, you can have a Titan retain all its gained XP after death. But without the research, Titans are reset to 0 when rebuilt.  
