Shiels, 64, replaced Alfie Wylie as boss in May 2019 and said he felt “really good” about agreeing a new deal.
“I want to contribute more and develop the under-19s’ best players, who have been with us for over a year now and they have developed to a really good level.
“Some of them are blossoming and almost ready to come in later down the line when we come back in June.
“We will gradually drip feed them back into the squad, so that they become the next Julie (Nelson), or the next Ash (Hutton) – whoever it may be.”
IFA chief Nelson added that the governing body is set to put “more time, effort and money” into the women’s game which will include appointing a full-time head of women’s football at the association.
“We’ve worked hard on it so far and we’ve made great strides off the field as well.
“We’ve going to have a director of women’s football in the near future. It’s going to be a really exciting role which drives women’s football forward and we’re looking for a great person to do that.”