Yes, via your EVA jetpack. What is your current orbit Pe and Ap? The higher your Ap, the easier this will be. At the Ap, point your shit retrograde, then EVA, the go to the butt of the shit and push directly against it. You should be able to line up exactly to retorgrade now that the navball shows in EVA. If you have Kerbal Engineer installed, you should be able to see your Pe come down in real time. If not, you have to check in the map, which might require you to get back into the ship. Not sure. Either way you have a good chunk of delta V in that jetpack. Be sure not to fully drain your jetpack in EVA. You can get back into your capsule and your jetopack mono propellant will be refilled. Rinse and repeat until Pe is where you want it.