Nobody can't predict future returns but if you see the past loyalty bonus of LIC plans (see the attached pdf)
Jeevan Shree* (plan 112) - 5 to 9 Years Term => 70 (Loyalty Addition per 1000 sum assured )
- 10 Years or more Term => 150 (Loyalty Addition per 1000 sum assured )
* No info about Jeevan Saral in the LIC Bonus Rates.
So if we assume that LIC Jeevan Saral will also give similar return then you may get upto 15% (as per above example).
LIC Bonus Rates 2008-09 - http://www.licindia.in/pages/Bonus_rate2008-2009.pdf