Complex sentence: Recently, Knoebels has posted that Project 2015 will be a new steel roller coaster named "Impulse" that will replace two former rides, the bumper boats and boat tag, both of which had been losing popularity, while maintenance costs became increasingly high.
Split into simpler sentences: Recently, Knoebels has posted that Project 2015 will be a new Steel roller coaster named "Impulse" that will replace two former rides, the bumper boats and boat tag. Both of which have been losing popularity, while maintenance costs became increasingly high.