How do I get my peonies to rebloom?

They may be buried too deep. This can happen over winter with freeze and thaw.

Vel

Hope these ideas help you out

https://www.gardeningknowhow.com/ornamental/flowers/peony/why-your-peony-buds-but-never-flowers.htm

https://www.wikihow.com/Get-Peonies-to-Bloom

If you've recently planted a new, nursery-grown peony, it may take several years to reach a size and maturity that can support flowering. It could take 3-4yrs. Planting peonies too deeply can also inhibit flowering, so position new plants or divisions so buds are no more than 1 or 2 inches below the soil surface.Although peonies benefit from rich soil that contains a good supply of nutrients, it's important to feed the plants properly and not use too much nitrogen, which can promote growth of stems and leaves at the expense of flowers. For best results, select a granular, low-nitrogen fertilizer such as 5-10-10, applying it at a rate of 2 to 3 pounds per 100 square feet of planted area. Apply the fertilizer once per season in the spring, when the plant's stems are about 3 inches tall, working it carefully into the ground. Keep fertilizer away from the plant's stems to prevent burning, and don't disturb tender new shoots; water the fertilizer in well.THey need at least six or more hours of full sun daily; a spot that gets too much shade can result in few or no flowers. If you have a peony that's recently stopped blooming, this could be because other nearby plants have become large and block the peony's access to light. Prune back surrounding plants as needed to give the peony more light, or consider relocating the peony to a brighter spot. Removing leaves and stems as you tidy the garden during the summer can also contribute to poor flowering because this weakens the plant and interferes with its ability to store energy for the next year. Delay cleanup until fall, when the plant's growth has slowed and foliage is wilted and partly dry.

Too many leaves and too few buds can also indicate excessive nitrogen fertilizer. Generally, established peonies do not need fertilizing.