Creeping Charlie, aka Creeping Jenny and ground ivy (and possibly many other names) "Glechoma hederacea", prefers to grow in poorer soils that will not grow a good, healthy turf. So the first step in control is a good, reliable soil test to see what might need be done to improve the soil since your best means of control is a good, healthy turf.
Spraying something to control any weed is simply treating the symptoms of the problem and is not a cure.

Here is a link that might be useful: About Creeping Charlie

You may have some roots that survived the herbicide treatment last year, or the lawn is well seeded down from years without treatment so you have a lot of seedlings. Your best long term results will be from thickening and re-invigorating the grass, however in the mean time continued treatments when the creeping charlie appears will control the new flushes without harming the established grass. Generally you will not need to treat more than a couple times a year, which will not be excessive or damage your established grass. By keeping the competition from the creeping charlie down, the grass will normally recover and thicken within a couple seasons. Just follow a normal fertilizing schedule, you won't need massive amounts as long as the competition from the creeping charlie can be kept down. This was how I handled the problem a few years ago and it worked well. I think I sprayed once or twice a season when the weeds were well leaved out, and probably fertilized the first year only. (I only fertilize every couple years normally).

Spraying any poison is detrimental to the environment you live in and spraying any poison more than once per year is an unnecessary expense. Correct the soil problems that exist, create a good, healthy soil for your grass to grow in and that grass will crowd out any "weeds" that wnat to grow there and most likely the "weeds" won't because they don;t like the soil conditions.