Increasing your Clan Level requires the following:

Clan Level 1: 35,000 SP plus 650,000 adena
Clan Level 2: 150,000 SP plus 2,500,000 adena
Clan Level 3: 500,000 SP plus Proof of Blood
Clan Level 4: 1,400,000 SP plus Proof of Alliance
or 1,400,000 SP plus 16,000,000 adena
Clan Level 5: 3,500,000 SP plus Proof of Aspiration
or 3,500,000 SP plus 30,000,000 adena