If your stropping technique is good -- you keep the spine on the strop, and don't press hard on the edge -- then:

. . . Give the razor a _good_ stropping -- like 100 laps fabric, followed by 200 laps leather.

If you're lucky, that may help restore the edge.

If that doesn't work, and you have a pasted strop (leather, cloth, or balsa, 0.5 micron CrOxide or diamond), do 10 laps on the pasted strop, and test the edge.

If that doesn't work, you'll have to rub it on a rock.

Charles

PS -- this is a re-phrasing of an earlier suggestion. The principle is:

. . . Remove only as much metal as you _must_ remove.