According to le chatelier's principle, when a change is introduced into a system in chemical equilibrium, the equilibrium shifts?

Yes it shifts depending on if the equation is product or reactant favored. Factors that can determine which way the equilibrium shifts could be pressure, movement, heat, a rise or fall in temperature, a catalyst (only if in the equation already), a gain or loss of a reactant, and a gain or loss of a product

If the experiment was perfomed more then once and you get the same results