Increasing CL Without Houseruling It:
Supernatural Transformation
(Savage Species, p. 39)
[General]
You convert a spell-like ability to a supernatural ability.
Prerequisite
Innate spell-like ability,
Benefit
One of your innate spell-like abilities becomes a supernatural ability. It is no longer subject to spell resistance, though it can still be suppressed in an anti-magic field. Using this ability does not provoke an attack of opportunity. The number of uses, if limited, does not change. The effective caster level equals your total Hit Dice or the effective caster level of the original ability, whichever is higher.
Special
You can gain this feat multiple times. Its effects do not stack. Each time you take it, it applies to a new spell-like ability.