In the SIR (Sequential Importance Resampling) particle filter, resampling aims to replicate particles that have gained high weight, while remove those with less weight.
So, when you have your particles weighted (typically with the likelihood you have used), one way to do resampling is to create the cumulative distribution of the weights, and then generate a random number following a uniform distribution and pick the particle corresponding to the slot of the CDF. This way there is more probability to select a particle that has more weight.
Also, don't forget to add some noise after generating replicas of particles, otherwise your point-estimate might be biased for a period of time.