Respawn is each 4 days in a Random moment in the day on Treasure Island. I found every week Two times ever on the 10PM BR Horary or at the Midnight. In Calassa The respawn can be one per week or every 15 days each.
Oramond u can force the respawn. Not is certainly know how much Titanicas Will appear when u are forcing.
Trust me. I have a lot of catchs but i lost on my discord.
And one in TibiaBosses XD - Titanica by Jin Toujo
If Titanica is dead she only will appear in other day. Not more of '1' in the same day.