Ok, so i recently hit rank 900, and realized the Xavox Stryll Punisher is no longer visible, which, i'll be honest, blows, because i still have plenty of planets that could use the interrogation strongholds, and im sure i will get more planets that could benefit from them in the future. and even if i didnt, they are still good for tech parts.
I think we can all agree, they are useful, and it sucks to see them go.
Now, the Easiest Answer, provided you are looking for one, would be to simply extend the upper-rank limit, like what was done with the Lazuli Plant or the Silthion Queen, but, i think, thats kind of boring, and repetitive.
So my suggestion is this: Add a new one, that comes in at, say, rank 900?

It could follow in the Trend of the Stryll Punisher. That way, it doesn't have to look much different either, it could simply be an upgraded version of the current one. Could be a simple fix, simply use the Xavox's Template, and change some of the details and graphics around slightly, and your done.

Svax, Stryll Punisher. (65-200)
Xavox, Stryll Punisher. (200-900)
I suggest:
Xavion, Stryll Punisher. (900-3200) For example.
Rank: 450.
Shields: 75,000.
Hull: 35,000.
Abilities: Stryll Disruption. (does what Stryll Disruption does, -20% defense)
Attack: 5,400.
Defense: 5,900.
Rewards: Interrogation Lab*. (could look just like the Stronghold, except Purple, which would be an easy and quick change)
Expires: After 24 Hours
Experience Earned on Kill: 120
It would be an Elite, share-able from 900-3200. top 3(or 4) players get rewarded.
*The Interrogation Lab, would be like an Interrogation Stronghold, except it gives 3 research, rather than 2, with the same size, and defense bonus.

So theres my suggestion.
I know a lot of people are gona say "to easy" "to hard" "not good enough rewards" "rewards are to good" "we dont need anything new" "random comment about the new Batman or Spiderman movies"
And to that i say: Alright, i understand your opinion, im just trying to get some new NPC's and artis added to the game, feel free to add, remove or change whatever you want.
Thank you.