Visiting canada to extend visitor visa

[abk_80]

My MIL's visitor visa expires soon and we have applied for an extention. However I am not sure if we will get an answer before her return date.
Can we go to canada and get a new i-94 while coming back? Are there any specific rules like staying in Canada for specific number of days etc?
Please help

[immihelp]

You can't do that. It is not allowed that way.