If it were me, I would just cap the last nap of the day and make it a shorter catnap. Then as she gets older and her awake time lengthens, the other two naps will be pushed out and the catnap will disappear as it will not be needed to make it from the second nap to bedtime. Ideally, you do want those other naps to be long so if you shorten them they will not be as restorative as they could be and if she is taking 2 hour naps generally I would want to give her the opportunity to continue having 2 solid, two hour naps and then maybe only an hour or less nap at the end of the day.
Have you read through the EASY sample routines?
chronological EASY samples, 4-6 monthsYou may find that to be helpful. Also, if you think she is waking for other reasons then you may not need to adjust the daytime schedule, but she is getting to an age where that may be a problem. 4 months is a weird developmental stage and usually coincides with a growth spurt. Those can cause night waking more often, too.