Why is my age non-refundable tax credit roughly half of the amount I was allowed in 2013? I am getting older, not younger..

Do you have more income in pensions or RIFFS than in 2013.  The age amount is income tested.

Per CRA:

You can claim this amount if you were 65 years of age or older on December 31, 2015, and your net income (line 236 of your return) is less than $82,353.

If your net income was:

• $35,466 or less, claim $7,033 on line 301 of Schedule 1, Federal Tax; or
• more than $35,466, but less than $82,353, complete the chart for line 301 on the Federal Worksheet to calculate your claim.