Hi, 

General care for house plants that don't seem to be performing well are more light and if they haven't been fertilized in awhile, you can add that. If you re-potted recently, it could be that the pot is too big for it. The calla lily needs to go through a dormant period and looks like that is new growth, so perhaps it will bloom this year with some sun and warm temperatures.

If you have a spot where they can be put outside as the weather warms up, that could help. You can acclimate them slowly by introducing them to limited amounts of sun for a few hours at a time. Peace Lily will like it bright but not full sun.

General growing tips for Peace lily from NC State Extension and Clemson Extension. Unfortunately we don't have a lot of detailed information on them.

Here are some detailed tips for growing Calla Lily: 

Calla Lily care

Calla Lilies are not reliably winter-hardy here but can be (and are best when) grown outdoors in dappled afternoon shade for the summer; afterwards they are either allowed to be killed by freezes or dug up and brought indoors before the fall frosts for storage until next May when it's safe to put them back outside. Calla Lilies are often sold potted in-bloom in spring (around the same time Easter Lilies and forced potted Tulips are out) or as dormant rhizomes in spring along with other non-hardy summer-blooming bulbs. When potted, they're usually intended to only be kept as long as the flowers last. You can keep them for years longer, but it can be challenging to give them the dormancy "rest period" they need.

They do not grow or keep leaves year-round; at some point, all of the leaves will be shed and the tubers will stay dormant for a few months. N.C. State suggests storing dormant tubers dry between about 50 and 60°F. Tips from the book The Complete Houseplant Survival Manual (by Barbara Pleasant, 2005) say to "allow the plants to dry until leaves wither, clip off the old foliage, and keep the pots very lightly moist in a cool, shady spot." This is for late summer; after this autumn dormancy, potting them up again in early winter in fresh soil and increasing light, moisture, and warmth will "wake" them up and restart growth.

When growing indoors, Callas need bright light (such as in a sunny window for several hours), cool temperatures (above 60 but below 75° F, though warmer in summer is ok), and fairly regular fertilizer (perhaps monthly). Excessive amounts of nitrogen may contribute to leaf/stem flopping, as will to too little light. Plants should be consistently moist (but not soggy) when in active growth, but allowed to dry more and more between waterings in late summer until they go dormant, at which point they should be allowed to dry out nearly completely. If not allowed to grow outdoors at all over the years, they may gradually weaken and decline until they don't perform well any more. Given a spring/summer outdoors, they may live longer, though we don't have data on exactly how long.

Also, you may find some guidance from vendors of Calla Lilies (and other spring and summer bulbs) online.

Emily