There's a few ways, depending on what you have available to you, and how bad you let it get between sharpenings.
Assuming you touch up often and don't have any crazy knicks to deal with:
OKAY - Stropping on a leather boot lace loaded with an abrasive compound
BETTER - Stropping on a profiled leather wheel loaded with compound on a slow speed grinder
Edge trailing stropping motions with 90% of the focus on the beveled face of the blade, light touch on the back side as flat as you can keep it, you want it to stay a chisel edge / single bevel /whatever term you like for that
If serious work is needed:
OKAY? - Many people say the corners on the spyderco tri-angle sharpmaker work well. Usual edge leading sharpening motion on the face, but a very light touch. Then a flat edge trailing stropping motion on the back to knock off the burr. I've only tried that once.... Worked okay, but i can't believe it won't round over the points eventually
BETTER? - takes longer, but i feel more confident about being able to do this without rounding the points...get yourself a set of small, fine diamond files in various shapes. Sharpen by filling the beveled faces individually. Knock off the burr by stropping the back side