It highly depends on how far you are over the (kind-of) arbitrarily chosen limit. If the IDE reports e.g. 76% I would not worry, if it is over 80% I will start worrying. The sketch itself will also have an affect how much RAM it uses at run time and if it's going to be a problem.
You don't seem to be willing to share your code; if it does not make use of the F macro for printing, that would be the first thing to do.
Define "same form" 
A shield designed for an Uno will fit on a Leonardo (500 bytes extra RAM) or a Mega (plenty of extra RAM but a lot bigger).
However, the shield needs to be properly designed meaning that:
- The 6-pin ICSP header needs to be used for SPI.
- I2C must be on the header that also has pins 8-13.
And if your sketch bypasses the hardware abstraction layer you have another problem.
Lastly note that not all libraries are compatible with the Nano Every (and the point of bypassing the hardware abstraction layer also stands). Before going that way I suggest that you compile for the Nano Every to find possible problems.
Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advice on) your project See About the IDE 1.x category.