I recommend sitting back and picking up your hands while adding some leg if this doesn’t help spurs are a good option if used correctly
When my horse starts to get lazy, I note this as him being stale/bored and a little disrespectful. I keep him interested in doing work by riding him in multiple rings and different surfaces. I also take him for regular hacks throughout the week, about 2-4 times this keeps his mental state good. If I’m doing this and my horse is still lazy my warmup consists of about 15 mins of walking to know that all his muscles are warmed up, I trot him on a loose rein large and lots of changing directions. Get him going as fast as you possibly can. Carry a crop and if he doesn’t responds give him a tap or smack where your heel rests. Hopefullly this sets up for a nicer canter :) you can do the same in the canter. Try standing in the canter and putting you hands forward as well.
I use a whip when riding him. It seems to help but nowhere near enough.
tried a dressage whip? Waving those to make a sound work for my lazy welsh cob
My trainer tells me to just kick and squeeze. If that does not work tap with a crop.