* putting the lighter in the fridge or freezer for awhile before refilling (causes much more effective and easier butane transfer from can to the lighter's internal tank).
* blowing canned/compressed air into the jets to clean them with pressurized air, and if that fails:
* BEING VERY CAREFUL TO AVOID ALL POSSIBLE IGNITION SOURCES INCLUDING MAKING SURE THE IGNITER CANNOT SPARK, then pressing a butane can's valve down on the (unlit!) jets to clean them with pressurized solvent (butane), while being careful not to bend or dislocate the spark-generating arm. (little-known but awesomely effective trick!)
* some lighters (including most Xikars) let you do a simple 2-minute procedure with a small screwdriver to adjust the flame adjustment wheel's range (which is a subset of the lighter's full possible range) into a higher or lower part of the lighter's full possible range (Xikar has a YouTube video about this, watch it).
* Xikar will replace your lighter with a brand new one as often as necessary forever, by mail or instantly over-the-counter at a dealer. If the above techniques don't work, this obviously will fix the problem, every time and forever. I recommend disregarding all other brands for this reason alone.