CC stands for Cubic Centimeter so changing your clutch won’t increase your CCs. Single speed engines aren’t great at hills in the first place. Air filter won’t help but is good for the bike so nothing that’s not supposed to get into your system will get in. You’ll have to rejet because you’re messing with the fuel/air mixture. Gear ratios are something to look at. You’ll lose some top speed but will gain torque therefore hill climbing ability and acceleration from off the block. Don’t let kits scare you, they’re arguably same level of complexity as fine tuning your clutch.