For example, if you want to resume an SIP that was originally of Rs10,000, and is now of Rs9,000. You can start a new SIP of Rs1,000 by selecting the same fund / same option / same folio number and it will get added to your original SIP. Registration of SIP takes 10-15 working days, so select a date for the new SIP to match the original SIP's date. For instance, if your original date was 20th of month, and today is 2nd or 3rd of the month, you will be able to get the same date as the earlier SIP and your SIP will start in this month itself. However, if today's date is, say, 10th and you select the starting date for the new SIP as 20th, it will start from next month.