Ys...if it is to find out the effect of concentration of the polymers on the different quality attributes you can go with increasing the weight...that is for research purpose...but if it is for market.. u have to fix the tablet weight and strictly follow the guidelines of the limits of tablet weight variation allowed...
Definitely polymer concentration can be increased to find out the effect of polymer over the action of the tablet.
Fix the concentration of the API and increase the concentration off the polymer. From that u can optimise the formulation among all number of formulations and carry-on further parametrs.