I wouldn't bother replacing him. If this is on either Diamond or Pearl, then just keep him; if you want a fire type, your only other option is Rapidash. If this is Platinum, though, and you still want a fire type, there's a handful to choose from. And why does the poor thing have two HMs? I could sit here and ask questions, but I'd rather answer yours. It learns Fire Spin at 39, which isn't a very powerful fire-type move. If I were you, I'd keep him and get the Flamethrower TM at Fuego Ironworks after you're able to Surf. If you'd rather not do that, Infernape learns Flare Blitz at level 57. Hope I could help.