Final answer:
The Roman Republic was not reestablished after Caesar's assassination because his heir, Octavian, consolidated power and transformed the political system into the principate, which was an autocracy in republican guise. The lack of political will from the Senate and general satisfaction among the populace with imperial governance further discouraged a return to the old republic.
Step-by-step explanation:
After Julius Caesar was assassinated, the restoration of the Roman Republic did not occur. Instead, a new chapter in the Caesarian dictatorship began with Caesar's grand-nephew and heir, Octavian. Despite the initial intentions of Caesar's assassins to save the Republic, Octavian took advantage of the situation, inheriting Caesar's wealth and securing his power to form the Second Triumvirate.
The Triumvirate eventually dissolved into conflict, but with the support of Caesar's veterans, Octavian emerged victorious, and in 27 BCE, he was given the honorary title of Augustus. Although he announced the restoration of the Republic, it was merely a formality to legitimize his new system of government, known as the principate, which was effectively an autocratic rule.
Furthermore, by the time of Augustus' death, there was no political will for a true republic, as radical change had benefited the common people and military, and the only real losers were the old patrician elite. The Roman citizens mostly enjoyed the stability and benefits provided by the imperial system, eroding any significant desire to return to the tumultuous republican system.