My suggestion would be that yes, you will need to go back to court. If he is at your home often and is staying overnight for more than one night consecutively during the week then regardless of paying rent somewhere else, it could look as though you are cohabitating. See the definition below from the Alimony section of the home site:
"Any motion to modify or terminate alimony or postseparation support based on a resumption of marital relations between parties who remain married to each other shall be determined pursuant to G.S. 52-10.2.
(b) If a dependent spouse who is receiving postseparation support or alimony from a supporting spouse under a judgment or order of a court of this State remarries or engages in cohabitation, the postseparation support or alimony shall terminate. Postseparation support or alimony shall terminate upon the death of either the supporting or the dependent spouse.
As used in this subsection, cohabitation means the act of two adults dwelling together continuously and habitually in a private heterosexual relationship, even if this relationship is not solemnized by marriage, or a private homosexual relationship. Cohabitation is evidenced by the voluntary mutual assumption of those marital rights, duties, and obligations which are usually manifested by married people, and which include, but are not necessarily dependent on, sexual relations. Nothing in this section shall be construed to make lawful conduct which is made unlawful by other statutes."
Hope this helps.