As pointed out by the other poster, you cannot treat time series data as a simple random sample due to the correlations between adjacent observations in time. A nice nonparametric approach to generating sample paths is the block boostrap and here http://nccur.lib.nccu.edu.tw/bitstream/140.119/35143/6/51007106.pdf
Note that the first link also points you to the handy tsboot package in R.