Below is an example of a macro I use to put rejuv on every target. Before I was trying to do what you were doing but I had the same problem with the castsequences moving forward.

/castsequence [@player1] reset=1 rejuv, null
/castsequence [@player2] reset=1 rejuv, rejuv, null
/castsequence [@player3] reset=1 rejuv, rejuv, rejuv, null
/castsequence [@player4] reset=1 rejuv, rejuv, rejuv, rejuv, null
/castsequence [@player5] reset=1 rejuv, rejuv, rejuv, rejuv, rejuv, null

Its not a perfect solution but it works.