The plan for "Cro Cop" is to have him fight three times in 2009, two under mixed martial arts rules and one in K-1 kickboxing.
His first fight could be in July against Alistair Overeem in kickboxing bout.
"Cro Cop" gave an update on his knee on Sunday in his first blog post since September on his MMA-ID blog.
"I'm training like a maniac and I'm definitely going to be ready for another comeback," Filipovic wrote. "So what is my next move? I need to finish the recovery process first and then take it from there. I should be able to use my leg for kicking in early May so I should be OK to fight 5 weeks from there."
Filipovic did not address where he will fight but did said he's aiming for three fights.
"I plan on having three fights this year and I won't be looking for a warm-up fight," he wrote. "I don't need to prove myself all over again to me or to the people that I care about, but I definitely need to show those people who counted Cro Cop out already that they were terribly wrong!"
"Cro Cop" had been in talks with the UFC to fight at UFC 99 in Cologne, Germany.