Three things to look at off the top of my head.
First, do you have the correct grain temperature entered on the mash tab. I keep my grains in the refrigerator until it is time to add them. This way they are consistently at 40 F and I don't have to take a measurement and make a last minute adjustment to the strike temperature.
Second, the same goes for the temperature of your equipment. Check and make sure it is consistent, especially if you are having BeerSmith take the temperature of the equipment into account when making the calculations for strike temperature.
Thirdly, check the weight of your equipment versus what is entered in the equipment profile. Again, this only comes into play if you are using the software to take this into consideration.
And fourth, you can adjust the specific heat of the equipment to account for heat loss to bring your hlt up to temperature.
Ok, so there were four things off the top of my head. But I would start with these, make the adjustments to the equipment profile as needed and then plug it back into one of the recipes you brewed already (make a copy of it so that you can compare back to the original, Adjust the mash profile to reflect your actual measured mash temp.) and see how the adjustment compares to your actual results.
Once the software seems to match your actual results, you know you are probably somewhere close. Use the next couple of brews to fine tune it from there.