Can you bury the pipe below the frostline?

Somewhere there must be a low spot in the line where water remains and then freezes. Once the pump shuts off, the line should be clear and there should be nothing to freeze. If there is a valve at the pump itself to prevent backflow, this could be the problem. Heat tapes are unlikely to be effective. The plastic pipe is a poor conducter of heat and the tapes do not put out very much; there is also the danger of malfunction and melting of the plastic. If you can find where water is remaining in the pipe and eliminate the cause, you will have no more freezing just as in the previous setup.

Ours freezes if it gets real cold (maybe 5 degrees?, but it may partially freeze above that). Our house is set on a flat area, but the back yard slopes to a pond in the back. The pipe exits the basement at the footer level and stays below the frost line except the last 5 feet or so. When it froze DH built a box with a lid to put over the area the pipe exits. He then put a heater in there. Once the slug of ice melted enough DH was able to pull it out. Now we keep the heater down there but only plug it in when it will get real cold (the outlet is on the porch, so easy to access).