1. A routing method comprising: (a) receiving a layout identifying a plurality of circuit components to be included in an integrated circuit (IC) layer for double patterning the layer using first and second photomasks, the layout including a plurality of first patterns to be included in the first photomask and at least one second pattern to be included in the second photomask; (b) receiving an identification of a selected one of the first patterns having first and second endpoints, to be replaced by a replacement pattern connecting the first endpoint to a third endpoint; (c) reserving at least one respective keep-out region adjacent to each respective remaining first pattern except for the selected first pattern; (d) generating data representing the replacement pattern, such that no part of the replacement pattern is formed in any of the keep-out regions; (e) outputting data representing the remaining first patterns and the replacement pattern to a machine readable storage medium to be read to fabricate the first photomask.