It'll need renewing at some point so why not get it out of the way?
We are also going in April. My sons expired last month and I've just sent off the renewal. The renewal only takes 3 weeks max and cost £54 or £49 if you don't want it sent back recorded delivery.
I just renewed my own too which I did online and was processed in a few days. It's a little more difficult for the child passport renewal as you have to send new photos and get them countersigned, but still just a simple online form and declaration to print out and sign.