Q.My Dieffenbachia Is 2 Yrs Old. Is It Too Late In The Summer To Repot? Will It Throw The Plant Into Shock?
Some of the leaves are yellow on the edges.

Certified GKH Gardening Expert
Yellowing leaves can indicate a rootbound plant. It also can indicate too much fertilizer, overwatering, nutrient issue, or insect problem, so check for those, too.
I think it will be fine if you want to repot. Remove the yellow leaves and just go up one pot size.
https://www.gardeningknowhow.com/houseplants/dumb-cane/growing-dumbcane-dieffenbachia.htm
https://www.gardeningknowhow.com/houseplants/hpgen/learn-more-about-repotting-houseplants.htm