Usually not, it will destroy whatever coagulation you have already gotten and the new rennet will not mix properly inside the curd that have already began to form. In some recipes of more acidic cheese you may be able to wait and see what happens. In harder cheeses it's more sensitive and you would be better off trying to make cheese with the poor curd than waiting longer for it to harden (as it will give you acidic crumbly dry cheese that can't even melt).
Watch out for the recipe and the rennet. Rennet comes in single and double strength, and strength in the US is different than in the EU. In the EU single strength rennet is 10,000:1 and double is 20,000:1, in the US single strength rennet is 15,000:1 an double is 30,000:1. (So single EU rennet for example will use 1 part to gel 10,000 parts)