If one is involved in haraam and after numerous trials, continues to fail at stopping their addiction to a sin, can they continue to try searching for a permanent spouse instead of mutah? Is such a person required to do mutah if a permanent spouse has not been found and the sinning continue despite multiple attempts to stop otherwise?

There are two options permanent marriage and Mutah. If one is unable to find spouse for permanent marriage then at least protect his nafs from sin by doing mutah.