I used to receive UCCB (until my third child turned 7). Now that the new UCCB covers children aged 6-17, do I need to apply for it all over again?

[kpclysdale]

TurboTax says "You can apply online by using “Apply for child benefits” through the CRA’s My Account or complete Form RC66, Canada Child Benefits Application, and send it to your tax centre with any required documentation identified on the form. Click the CRA link below to find this form.", but there isn't a link below.

[TonyC11 · Accepted solution]

Both CRA and Service Canada are still referring to this change to UCCB as 'proposed' at least on their web pages. Both say that CCTB recipients do not need to apply for UCCB, but that is true of the existing program anyway.

The upshot is that I don't see a definitive answer to your question yet. However I'd recommend that you submit a new RC66. Just google RC66 and you will find the firm available to fill.
You could also contact Service Canada.

[pmcclure1812]

I am in exactly the same situation. My children are 10,15, and 16. My wife used to receive CCTB (or UCCB? or both?), but that stopped 4 years ago when my daughter turned 7 (I think). Will my wife automatically get the new UCCB after this 4 year gap? Or does she need to re-apply? I cannot seem to find an answer to this.

[pmcclure1812]

Ignore that. "Pete from the Hammer" has provided the answer below. Thank you Pete.

[Pete-from-the-Hammer]

According the CRA webpage on the Enhanced Universal Child Care Benefit, you DO NOT have to re-apply. 

While I currently do not receive the UCCB or the CCTB for my child, I previously applied in the past for these benefits. Do I have to reapply to receive the increased UCCB?

No. You will automatically receive the enhanced UCCB for your child.

(Above captured 2015/03/26 with page notation that last modification was 2014/10/31)

Reference: http://www.cra-arc.gc.ca/gncy/bdgt/2014/qa11-eng.html

[TonyC11]

As I understand from these answers on the web page of CRA, if you have never yet applied for UCCB and CCTB then you must submit an RC66.
But if you did at one time apply for UCCB and CCTB then you won't need to apply again.

[Pete-from-the-Hammer]

OP stated they previously received the benefit.  Therefore, the correct answer based on the current CRA entry is simply, No, you DO NOT need to re-apply.