With Formula 1 switching to the very different V6 turbo-powered rules next season, there will be scant carry-over between this year's cars and their successors.
While larger teams are optimistic they can keep upgrading their current designs until the end of the fight without any impact on 2014 preparations, di Resta thinks it will be tougher for Force India.
"When you have smaller resources, you are going to be more compromised," he said. "Whether that is going to be this year or next year, I don't know.
"It's whether they are going to be able to pump more into next year's car; whether a team like us can keep working away [on the current car] because the pressure is not about coming out at the top next year as it is for the likes of Ferrari and McLaren."
Di Resta thinks many teams will stop work on their 2013 machines in the summer.
"What's more important is that you have a good rate of development until June or July. Then they will switch off," he said.
"How much do you focus on a car that goes out of date in the middle of November?
"My aim would be to develop as much as you can until June and then essentially it will stabilise a lot. That will be interesting, seeing where people stabilise."
Force India has begun the 2013 F1 season as the fifth-quickest package behind Red Bull, Ferrari, Lotus and Mercedes, but di Resta reckons strenuous effort will be required to maintain that.
"It needs to stay where it is or get better because people will react fairly quickly," he said.
"I don't think you can underestimate anybody when you are racing McLaren and Sauber.
"They are teams with a lot of power behind them and can put a lot of pressure on you."
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