No other racial powers get new tricks at high level. Dragonbreath doesn't suddenly get ongoing damage or a push effect, so your attack should be static in what it does, and just scale in the damage.
Instead of full-on daze, I'd make a version that still keeps the enemy from reacting, but doesn't hose solos.
I'd go with:
Mind Flayer
Racial Traits- Average Height 5'6"-6'5", Average Weight 110- 160 lbs.
Ability Scores- +2 Intelligence, +2 Wisdom or +2 Charisma
Size- Medium
Speed- 6 squares
Vision- Low-Light
Languages: Common, Deep Speech
Skill Bonuses: +2 Bluff, +2 Insight
Aberrant Origin: Your ancestors are native to the Far Realm, so you are considered an Aberrant creature for the purpose of effects relating to a creature origin.
Illithid's Superior Will: You gain +1 racial bonus to your Will defense. In addition, you gain a +2 saving throw bonus to effects that daze, stun, and dominate you.
Tentacles: You can grab creatures with your tentacles as if it were a free hand. Creatures take a -2 penalty to skill checks to escape your grabs. Also, you can use tentacle grab as an at-will power.
Tentacle Grab
At-Will
Standard Action Melee 1
Target: One Creature
Attack: Intelligence, Wisdom, or Charisma +2 vs Will; +4 at 11th level; +6 at 21st level
Hit: 1d6 + Int/Wis/Cha modifier damage and you grab the target. If this damage reduces the target to 0 hit points, you can choose to eat the target's brain. If you do, you may spend a healing surge to heal.
Effect: You can sustain the grab as a minor action as normal, or you can sustain it by spending a standard action. If you spend a standard action, you deal damage to the target (and can potentially eat its brain) as if you had hit again with this power.
11th Level: 2d6 + Int/Wis/Cha damage.
21st Level: 3d6 + Int/Wis/Cha damage.
Mind Blast: You can use mind blast as an encounter power.
Mind Blast
Encounter* Psionic, Psychic
Standard Action Range 5
Target: One Creature
Attack: Intelligence, Wisdom, or Charisma +2 vs Will; +4 at 11th level; +6 at 21st level
Hit: 1d4 + Int/Wis/Cha modifier psychic damage, and the target grants combat advantage and cannot take immediate or opportunity actions until the end of your next turn.
11th Level: 2d4 + Int/Wis/Cha damage.
21st Level: 3d4 + Int/Wis/Cha damage.