They are 10 years old and border our front yard, look shabby even with regular care. Questions: can we completely prune down, dig up, ( they are planted too high) amend soil and replant? Or is this the end of lifespan?

Welcome to ATP. Carpet roses have a longer lifespan than 10 years in most cases, so that's not the problem. Why don't you amend the soil from the top? Just add lots of good soil and amendments to your existing beds. That would eliminate the problem of having the roses planted too high and would eliminate the need to dig them up and replant them. Pruning them should help, but you should do it at the proper time. We don't know where you live, so we can't advise you on the proper pruning time.

I agree with zuzu. Topdressing your roses with compost or your amendments of choice will help.

Regular watering, feeding with rose food like Rose Tone may also help.

You can dead head and trim the shrubs a bit anytime. Pruning roses for the first time is daunting. Paul Zimmerman has some good videos on rose training and pruning and a good rose gardening blog. You can find links on the FineGardening site.

Make sure you have white glue (Elmer's or similar) with you while pruning. Use the glue to seal the ends of cut canes wider that a pencil to prevent boring insects from damaging the rose.

I am establishing new beds this year. Am using either carpet or shrub roses. Because they new and small I have some concerns for the winter (zone 5a Maine). Can and should they be covered by inverted large flower pots to protect them from the snow?
Chuck

Carpet roses are tough! They'll be fine left exposed. As far as pruning goes, carpet roses have dozens of tiny branches, so shape with the hedge trimmers, and leave the glue in the house! We have some that stay nice and dense but get 4' tall, and others that I cut short in spring.