DLA - When/How to Apply for Updates?

[SpoilerFree]

I have DLA for my eldest atm, but it needs to be updated (turned 5, needs mobility and possibly a review of the care part as well). It doesn't expire for another 2 years, so how do I go about updating it? Do I resend the same form again or are there different forms for updates (and where to get them if so)?

Similarly if I was approaching the end of the allowance period, do I resend the same form and if so, at what point? Weeks before? As soon as it ends?

Thank you all in advance for your advice!

If you want the award reviewed you can call to request a change of circumstances.

At renewal time you will receive forms a few months before the end date.