Potty training help!

My son is 4 years old, almost 5. He is potty trained during the day. We started him at night as well in the beginning of November. He was doing amazing (only about 2 accidents). Then we went out of state from the 9th to the 18th and he only had one accident there. Now that we are home again he has been having accidents every single night. We have always given him milk at night, I have even cut it down to half of a cup only. And we make him go to the bathroom at 8pm and 10pm. What else can I do besides cut him off of drinks completely? It's becoming a lot to have to wash his sheets and blankets every day