Reset from Checks phase in SUM

Hello all,

I need some advice about upgrade with SUM Tool,

I had for 7 week ago start SUM tool to upgrade SAP ABAP installation
and I was finished with Check Phase on that time. The system is on frozen zone.

My question is can I continue with this upgrade after so long and go to
preprocessing phase. Or I should reset the upgrade and start with a new SUM
from scratch. 

Thanks

Reza