As part of a plea agreement, Servis admitted to two counts of accosting a child for immoral purposes. He was also charged as a habitual offender.
In exchange, prosecutors dropped two other charges involving possession of child pornography.
Servis, 42, was arrested June 29 after he approached three underage boys at Ideal Park. The boys left home and told family members, who then located and detained him until officials arrived.
In 2011, Servis was released from prison after serving more than eight years for sex crimes, including ones similar to what he did in this case. He is scheduled to be sentenced Jan. 9.