"Didst again" is an archaic form of the phrase "did again." The word "did" is the past tense of "do," and "didst" is an old-fashioned version of "did" that is no longer commonly used. Some synonyms for "didst again" include "performed once more," "repeated the action," "carried out again," "executed a second time," "duplicated the task," "redid the work," and "undertook anew." While "didst again" may not be a phrase that is in vogue today, it is interesting to note how language has evolved over time and how these archaic phrases still have relevance in our modern language.